xref: /freebsd-11.0-release/sys/amd64/amd64/machdep.c

/*-
 * Copyright (c) 1992 Terrence R. Lambert.
 * Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)machdep.c	7.4 (Berkeley) 6/3/91
 * $FreeBSD: head/sys/amd64/amd64/machdep.c 112883 2003-03-31 22:02:38Z jeff $
 */

#include "opt_atalk.h"
#include "opt_compat.h"
#include "opt_cpu.h"
#include "opt_ddb.h"
#include "opt_inet.h"
#include "opt_ipx.h"
#include "opt_isa.h"
#include "opt_maxmem.h"
#include "opt_msgbuf.h"
#include "opt_npx.h"
#include "opt_perfmon.h"
#include "opt_kstack_pages.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/signalvar.h>
#include <sys/imgact.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/linker.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/pcpu.h>
#include <sys/proc.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/reboot.h>
#include <sys/callout.h>
#include <sys/msgbuf.h>
#include <sys/sched.h>
#include <sys/sysent.h>
#include <sys/sysctl.h>
#include <sys/ucontext.h>
#include <sys/vmmeter.h>
#include <sys/bus.h>
#include <sys/eventhandler.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_pager.h>
#include <vm/vm_extern.h>

#include <sys/user.h>
#include <sys/exec.h>
#include <sys/cons.h>

#include <ddb/ddb.h>

#include <net/netisr.h>

#include <machine/cpu.h>
#include <machine/cputypes.h>
#include <machine/reg.h>
#include <machine/clock.h>
#include <machine/specialreg.h>
#include <machine/bootinfo.h>
#include <machine/md_var.h>
#include <machine/pc/bios.h>
#include <machine/pcb_ext.h>		/* pcb.h included via sys/user.h */
#include <machine/proc.h>
#ifdef PERFMON
#include <machine/perfmon.h>
#endif
#ifdef SMP
#include <machine/privatespace.h>
#include <machine/smp.h>
#endif

#include <i386/isa/icu.h>
#include <i386/isa/intr_machdep.h>
#include <isa/rtc.h>
#include <machine/vm86.h>
#include <sys/ptrace.h>
#include <machine/sigframe.h>

extern void init386(int first);
extern void dblfault_handler(void);

extern void printcpuinfo(void);	/* XXX header file */
extern void finishidentcpu(void);
extern void panicifcpuunsupported(void);
extern void initializecpu(void);

#define	CS_SECURE(cs)		(ISPL(cs) == SEL_UPL)
#define	EFL_SECURE(ef, oef)	((((ef) ^ (oef)) & ~PSL_USERCHANGE) == 0)

#if !defined(CPU_ENABLE_SSE) && defined(I686_CPU)
#define CPU_ENABLE_SSE
#endif
#if defined(CPU_DISABLE_SSE)
#undef CPU_ENABLE_SSE
#endif

static void cpu_startup(void *);
static void fpstate_drop(struct thread *td);
static void get_fpcontext(struct thread *td, mcontext_t *mcp);
static int  set_fpcontext(struct thread *td, const mcontext_t *mcp);
#ifdef CPU_ENABLE_SSE
static void set_fpregs_xmm(struct save87 *, struct savexmm *);
static void fill_fpregs_xmm(struct savexmm *, struct save87 *);
#endif /* CPU_ENABLE_SSE */
SYSINIT(cpu, SI_SUB_CPU, SI_ORDER_FIRST, cpu_startup, NULL)

int	_udatasel, _ucodesel;
u_int	atdevbase;

#if defined(SWTCH_OPTIM_STATS)
extern int swtch_optim_stats;
SYSCTL_INT(_debug, OID_AUTO, swtch_optim_stats,
	CTLFLAG_RD, &swtch_optim_stats, 0, "");
SYSCTL_INT(_debug, OID_AUTO, tlb_flush_count,
	CTLFLAG_RD, &tlb_flush_count, 0, "");
#endif

int cold = 1;

#ifdef COMPAT_43
static void osendsig(sig_t catcher, int sig, sigset_t *mask, u_long code);
#endif
#ifdef COMPAT_FREEBSD4
static void freebsd4_sendsig(sig_t catcher, int sig, sigset_t *mask,
    u_long code);
#endif

long Maxmem = 0;

vm_paddr_t phys_avail[10];

/* must be 2 less so 0 0 can signal end of chunks */
#define PHYS_AVAIL_ARRAY_END ((sizeof(phys_avail) / sizeof(vm_offset_t)) - 2)

struct kva_md_info kmi;

static struct trapframe proc0_tf;
#ifndef SMP
static struct pcpu __pcpu;
#endif

struct mtx icu_lock;

static void
cpu_startup(dummy)
	void *dummy;
{
	/*
	 * Good {morning,afternoon,evening,night}.
	 */
	startrtclock();
	printcpuinfo();
	panicifcpuunsupported();
#ifdef PERFMON
	perfmon_init();
#endif
	printf("real memory  = %ju (%ju MB)\n", ptoa((uintmax_t)Maxmem),
	    ptoa((uintmax_t)Maxmem) / 1048576);
	/*
	 * Display any holes after the first chunk of extended memory.
	 */
	if (bootverbose) {
		int indx;

		printf("Physical memory chunk(s):\n");
		for (indx = 0; phys_avail[indx + 1] != 0; indx += 2) {
			vm_paddr_t size;

			size = phys_avail[indx + 1] - phys_avail[indx];
			printf(
			    "0x%016jx - 0x%016jx, %ju bytes (%ju pages)\n",
			    (uintmax_t)phys_avail[indx],
			    (uintmax_t)phys_avail[indx + 1] - 1,
			    (uintmax_t)size, (uintmax_t)size / PAGE_SIZE);
		}
	}

	vm_ksubmap_init(&kmi);

	printf("avail memory = %ju (%ju MB)\n",
	    ptoa((uintmax_t)cnt.v_free_count),
	    ptoa((uintmax_t)cnt.v_free_count) / 1048576);

	/*
	 * Set up buffers, so they can be used to read disk labels.
	 */
	bufinit();
	vm_pager_bufferinit();

#ifndef SMP
	/* For SMP, we delay the cpu_setregs() until after SMP startup. */
	cpu_setregs();
#endif
}

/*
 * Send an interrupt to process.
 *
 * Stack is set up to allow sigcode stored
 * at top to call routine, followed by kcall
 * to sigreturn routine below.  After sigreturn
 * resets the signal mask, the stack, and the
 * frame pointer, it returns to the user
 * specified pc, psl.
 */
#ifdef COMPAT_43
static void
osendsig(catcher, sig, mask, code)
	sig_t catcher;
	int sig;
	sigset_t *mask;
	u_long code;
{
	struct osigframe sf, *fp;
	struct proc *p;
	struct thread *td;
	struct sigacts *psp;
	struct trapframe *regs;
	int oonstack;

	td = curthread;
	p = td->td_proc;
	PROC_LOCK_ASSERT(p, MA_OWNED);
	psp = p->p_sigacts;
	regs = td->td_frame;
	oonstack = sigonstack(regs->tf_esp);

	/* Allocate space for the signal handler context. */
	if ((p->p_flag & P_ALTSTACK) && !oonstack &&
	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
		fp = (struct osigframe *)(p->p_sigstk.ss_sp +
		    p->p_sigstk.ss_size - sizeof(struct osigframe));
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
		p->p_sigstk.ss_flags |= SS_ONSTACK;
#endif
	} else
		fp = (struct osigframe *)regs->tf_esp - 1;
	PROC_UNLOCK(p);

	/* Translate the signal if appropriate. */
	if (p->p_sysent->sv_sigtbl && sig <= p->p_sysent->sv_sigsize)
		sig = p->p_sysent->sv_sigtbl[_SIG_IDX(sig)];

	/* Build the argument list for the signal handler. */
	sf.sf_signum = sig;
	sf.sf_scp = (register_t)&fp->sf_siginfo.si_sc;
	PROC_LOCK(p);
	if (SIGISMEMBER(p->p_sigacts->ps_siginfo, sig)) {
		/* Signal handler installed with SA_SIGINFO. */
		sf.sf_arg2 = (register_t)&fp->sf_siginfo;
		sf.sf_siginfo.si_signo = sig;
		sf.sf_siginfo.si_code = code;
		sf.sf_ahu.sf_action = (__osiginfohandler_t *)catcher;
	} else {
		/* Old FreeBSD-style arguments. */
		sf.sf_arg2 = code;
		sf.sf_addr = regs->tf_err;
		sf.sf_ahu.sf_handler = catcher;
	}
	PROC_UNLOCK(p);

	/* Save most if not all of trap frame. */
	sf.sf_siginfo.si_sc.sc_eax = regs->tf_eax;
	sf.sf_siginfo.si_sc.sc_ebx = regs->tf_ebx;
	sf.sf_siginfo.si_sc.sc_ecx = regs->tf_ecx;
	sf.sf_siginfo.si_sc.sc_edx = regs->tf_edx;
	sf.sf_siginfo.si_sc.sc_esi = regs->tf_esi;
	sf.sf_siginfo.si_sc.sc_edi = regs->tf_edi;
	sf.sf_siginfo.si_sc.sc_cs = regs->tf_cs;
	sf.sf_siginfo.si_sc.sc_ds = regs->tf_ds;
	sf.sf_siginfo.si_sc.sc_ss = regs->tf_ss;
	sf.sf_siginfo.si_sc.sc_es = regs->tf_es;
	sf.sf_siginfo.si_sc.sc_fs = regs->tf_fs;
	sf.sf_siginfo.si_sc.sc_gs = rgs();
	sf.sf_siginfo.si_sc.sc_isp = regs->tf_isp;

	/* Build the signal context to be used by osigreturn(). */
	sf.sf_siginfo.si_sc.sc_onstack = (oonstack) ? 1 : 0;
	SIG2OSIG(*mask, sf.sf_siginfo.si_sc.sc_mask);
	sf.sf_siginfo.si_sc.sc_sp = regs->tf_esp;
	sf.sf_siginfo.si_sc.sc_fp = regs->tf_ebp;
	sf.sf_siginfo.si_sc.sc_pc = regs->tf_eip;
	sf.sf_siginfo.si_sc.sc_ps = regs->tf_eflags;
	sf.sf_siginfo.si_sc.sc_trapno = regs->tf_trapno;
	sf.sf_siginfo.si_sc.sc_err = regs->tf_err;

	/*
	 * If we're a vm86 process, we want to save the segment registers.
	 * We also change eflags to be our emulated eflags, not the actual
	 * eflags.
	 */
	if (regs->tf_eflags & PSL_VM) {
		/* XXX confusing names: `tf' isn't a trapframe; `regs' is. */
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86 = &td->td_pcb->pcb_ext->ext_vm86;

		sf.sf_siginfo.si_sc.sc_gs = tf->tf_vm86_gs;
		sf.sf_siginfo.si_sc.sc_fs = tf->tf_vm86_fs;
		sf.sf_siginfo.si_sc.sc_es = tf->tf_vm86_es;
		sf.sf_siginfo.si_sc.sc_ds = tf->tf_vm86_ds;

		if (vm86->vm86_has_vme == 0)
			sf.sf_siginfo.si_sc.sc_ps =
			    (tf->tf_eflags & ~(PSL_VIF | PSL_VIP)) |
			    (vm86->vm86_eflags & (PSL_VIF | PSL_VIP));

		/* See sendsig() for comments. */
		tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
	}

	/*
	 * Copy the sigframe out to the user's stack.
	 */
	if (copyout(&sf, fp, sizeof(*fp)) != 0) {
#ifdef DEBUG
		printf("process %ld has trashed its stack\n", (long)p->p_pid);
#endif
		PROC_LOCK(p);
		sigexit(td, SIGILL);
	}

	regs->tf_esp = (int)fp;
	regs->tf_eip = PS_STRINGS - szosigcode;
	regs->tf_eflags &= ~PSL_T;
	regs->tf_cs = _ucodesel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	load_gs(_udatasel);
	regs->tf_ss = _udatasel;
	PROC_LOCK(p);
}
#endif /* COMPAT_43 */

#ifdef COMPAT_FREEBSD4
static void
freebsd4_sendsig(catcher, sig, mask, code)
	sig_t catcher;
	int sig;
	sigset_t *mask;
	u_long code;
{
	struct sigframe4 sf, *sfp;
	struct proc *p;
	struct thread *td;
	struct sigacts *psp;
	struct trapframe *regs;
	int oonstack;

	td = curthread;
	p = td->td_proc;
	PROC_LOCK_ASSERT(p, MA_OWNED);
	psp = p->p_sigacts;
	regs = td->td_frame;
	oonstack = sigonstack(regs->tf_esp);

	/* Save user context. */
	bzero(&sf, sizeof(sf));
	sf.sf_uc.uc_sigmask = *mask;
	sf.sf_uc.uc_stack = p->p_sigstk;
	sf.sf_uc.uc_stack.ss_flags = (p->p_flag & P_ALTSTACK)
	    ? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
	sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
	sf.sf_uc.uc_mcontext.mc_gs = rgs();
	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_fs, sizeof(*regs));

	/* Allocate space for the signal handler context. */
	if ((p->p_flag & P_ALTSTACK) != 0 && !oonstack &&
	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
		sfp = (struct sigframe4 *)(p->p_sigstk.ss_sp +
		    p->p_sigstk.ss_size - sizeof(struct sigframe4));
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
		p->p_sigstk.ss_flags |= SS_ONSTACK;
#endif
	} else
		sfp = (struct sigframe4 *)regs->tf_esp - 1;
	PROC_UNLOCK(p);

	/* Translate the signal if appropriate. */
	if (p->p_sysent->sv_sigtbl && sig <= p->p_sysent->sv_sigsize)
		sig = p->p_sysent->sv_sigtbl[_SIG_IDX(sig)];

	/* Build the argument list for the signal handler. */
	sf.sf_signum = sig;
	sf.sf_ucontext = (register_t)&sfp->sf_uc;
	PROC_LOCK(p);
	if (SIGISMEMBER(p->p_sigacts->ps_siginfo, sig)) {
		/* Signal handler installed with SA_SIGINFO. */
		sf.sf_siginfo = (register_t)&sfp->sf_si;
		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;

		/* Fill in POSIX parts */
		sf.sf_si.si_signo = sig;
		sf.sf_si.si_code = code;
		sf.sf_si.si_addr = (void *)regs->tf_err;
	} else {
		/* Old FreeBSD-style arguments. */
		sf.sf_siginfo = code;
		sf.sf_addr = regs->tf_err;
		sf.sf_ahu.sf_handler = catcher;
	}
	PROC_UNLOCK(p);

	/*
	 * If we're a vm86 process, we want to save the segment registers.
	 * We also change eflags to be our emulated eflags, not the actual
	 * eflags.
	 */
	if (regs->tf_eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86 = &td->td_pcb->pcb_ext->ext_vm86;

		sf.sf_uc.uc_mcontext.mc_gs = tf->tf_vm86_gs;
		sf.sf_uc.uc_mcontext.mc_fs = tf->tf_vm86_fs;
		sf.sf_uc.uc_mcontext.mc_es = tf->tf_vm86_es;
		sf.sf_uc.uc_mcontext.mc_ds = tf->tf_vm86_ds;

		if (vm86->vm86_has_vme == 0)
			sf.sf_uc.uc_mcontext.mc_eflags =
			    (tf->tf_eflags & ~(PSL_VIF | PSL_VIP)) |
			    (vm86->vm86_eflags & (PSL_VIF | PSL_VIP));

		/*
		 * Clear PSL_NT to inhibit T_TSSFLT faults on return from
		 * syscalls made by the signal handler.  This just avoids
		 * wasting time for our lazy fixup of such faults.  PSL_NT
		 * does nothing in vm86 mode, but vm86 programs can set it
		 * almost legitimately in probes for old cpu types.
		 */
		tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
	}

	/*
	 * Copy the sigframe out to the user's stack.
	 */
	if (copyout(&sf, sfp, sizeof(*sfp)) != 0) {
#ifdef DEBUG
		printf("process %ld has trashed its stack\n", (long)p->p_pid);
#endif
		PROC_LOCK(p);
		sigexit(td, SIGILL);
	}

	regs->tf_esp = (int)sfp;
	regs->tf_eip = PS_STRINGS - szfreebsd4_sigcode;
	regs->tf_eflags &= ~PSL_T;
	regs->tf_cs = _ucodesel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	regs->tf_ss = _udatasel;
	PROC_LOCK(p);
}
#endif	/* COMPAT_FREEBSD4 */

void
sendsig(catcher, sig, mask, code)
	sig_t catcher;
	int sig;
	sigset_t *mask;
	u_long code;
{
	struct sigframe sf, *sfp;
	struct proc *p;
	struct thread *td;
	struct sigacts *psp;
	char *sp;
	struct trapframe *regs;
	int oonstack;

	td = curthread;
	p = td->td_proc;
	PROC_LOCK_ASSERT(p, MA_OWNED);
	psp = p->p_sigacts;
#ifdef COMPAT_FREEBSD4
	if (SIGISMEMBER(psp->ps_freebsd4, sig)) {
		freebsd4_sendsig(catcher, sig, mask, code);
		return;
	}
#endif
#ifdef COMPAT_43
	if (SIGISMEMBER(psp->ps_osigset, sig)) {
		osendsig(catcher, sig, mask, code);
		return;
	}
#endif
	regs = td->td_frame;
	oonstack = sigonstack(regs->tf_esp);

	/* Save user context. */
	bzero(&sf, sizeof(sf));
	sf.sf_uc.uc_sigmask = *mask;
	sf.sf_uc.uc_stack = p->p_sigstk;
	sf.sf_uc.uc_stack.ss_flags = (p->p_flag & P_ALTSTACK)
	    ? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
	sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
	sf.sf_uc.uc_mcontext.mc_gs = rgs();
	bcopy(regs, &sf.sf_uc.uc_mcontext.mc_fs, sizeof(*regs));
	sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext); /* magic */
	get_fpcontext(td, &sf.sf_uc.uc_mcontext);
	fpstate_drop(td);

	/* Allocate space for the signal handler context. */
	if ((p->p_flag & P_ALTSTACK) != 0 && !oonstack &&
	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
		sp = p->p_sigstk.ss_sp +
		    p->p_sigstk.ss_size - sizeof(struct sigframe);
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
		p->p_sigstk.ss_flags |= SS_ONSTACK;
#endif
	} else
		sp = (char *)regs->tf_esp - sizeof(struct sigframe);
	/* Align to 16 bytes. */
	sfp = (struct sigframe *)((unsigned int)sp & ~0xF);
	PROC_UNLOCK(p);

	/* Translate the signal if appropriate. */
	if (p->p_sysent->sv_sigtbl && sig <= p->p_sysent->sv_sigsize)
		sig = p->p_sysent->sv_sigtbl[_SIG_IDX(sig)];

	/* Build the argument list for the signal handler. */
	sf.sf_signum = sig;
	sf.sf_ucontext = (register_t)&sfp->sf_uc;
	PROC_LOCK(p);
	if (SIGISMEMBER(p->p_sigacts->ps_siginfo, sig)) {
		/* Signal handler installed with SA_SIGINFO. */
		sf.sf_siginfo = (register_t)&sfp->sf_si;
		sf.sf_ahu.sf_action = (__siginfohandler_t *)catcher;

		/* Fill in POSIX parts */
		sf.sf_si.si_signo = sig;
		sf.sf_si.si_code = code;
		sf.sf_si.si_addr = (void *)regs->tf_err;
	} else {
		/* Old FreeBSD-style arguments. */
		sf.sf_siginfo = code;
		sf.sf_addr = regs->tf_err;
		sf.sf_ahu.sf_handler = catcher;
	}
	PROC_UNLOCK(p);

	/*
	 * If we're a vm86 process, we want to save the segment registers.
	 * We also change eflags to be our emulated eflags, not the actual
	 * eflags.
	 */
	if (regs->tf_eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86 = &td->td_pcb->pcb_ext->ext_vm86;

		sf.sf_uc.uc_mcontext.mc_gs = tf->tf_vm86_gs;
		sf.sf_uc.uc_mcontext.mc_fs = tf->tf_vm86_fs;
		sf.sf_uc.uc_mcontext.mc_es = tf->tf_vm86_es;
		sf.sf_uc.uc_mcontext.mc_ds = tf->tf_vm86_ds;

		if (vm86->vm86_has_vme == 0)
			sf.sf_uc.uc_mcontext.mc_eflags =
			    (tf->tf_eflags & ~(PSL_VIF | PSL_VIP)) |
			    (vm86->vm86_eflags & (PSL_VIF | PSL_VIP));

		/*
		 * Clear PSL_NT to inhibit T_TSSFLT faults on return from
		 * syscalls made by the signal handler.  This just avoids
		 * wasting time for our lazy fixup of such faults.  PSL_NT
		 * does nothing in vm86 mode, but vm86 programs can set it
		 * almost legitimately in probes for old cpu types.
		 */
		tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
	}

	/*
	 * Copy the sigframe out to the user's stack.
	 */
	if (copyout(&sf, sfp, sizeof(*sfp)) != 0) {
#ifdef DEBUG
		printf("process %ld has trashed its stack\n", (long)p->p_pid);
#endif
		PROC_LOCK(p);
		sigexit(td, SIGILL);
	}

	regs->tf_esp = (int)sfp;
	regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode);
	regs->tf_eflags &= ~PSL_T;
	regs->tf_cs = _ucodesel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	regs->tf_ss = _udatasel;
	PROC_LOCK(p);
}

/*
 * System call to cleanup state after a signal
 * has been taken.  Reset signal mask and
 * stack state from context left by sendsig (above).
 * Return to previous pc and psl as specified by
 * context left by sendsig. Check carefully to
 * make sure that the user has not modified the
 * state to gain improper privileges.
 *
 * MPSAFE
 */
#ifdef COMPAT_43
int
osigreturn(td, uap)
	struct thread *td;
	struct osigreturn_args /* {
		struct osigcontext *sigcntxp;
	} */ *uap;
{
	struct osigcontext sc;
	struct trapframe *regs;
	struct osigcontext *scp;
	struct proc *p = td->td_proc;
	int eflags, error;

	regs = td->td_frame;
	error = copyin(uap->sigcntxp, &sc, sizeof(sc));
	if (error != 0)
		return (error);
	scp = &sc;
	eflags = scp->sc_ps;
	if (eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86;

		/*
		 * if pcb_ext == 0 or vm86_inited == 0, the user hasn't
		 * set up the vm86 area, and we can't enter vm86 mode.
		 */
		if (td->td_pcb->pcb_ext == 0)
			return (EINVAL);
		vm86 = &td->td_pcb->pcb_ext->ext_vm86;
		if (vm86->vm86_inited == 0)
			return (EINVAL);

		/* Go back to user mode if both flags are set. */
		if ((eflags & PSL_VIP) && (eflags & PSL_VIF))
			trapsignal(td, SIGBUS, 0);

		if (vm86->vm86_has_vme) {
			eflags = (tf->tf_eflags & ~VME_USERCHANGE) |
			    (eflags & VME_USERCHANGE) | PSL_VM;
		} else {
			vm86->vm86_eflags = eflags;	/* save VIF, VIP */
			eflags = (tf->tf_eflags & ~VM_USERCHANGE) |
			    (eflags & VM_USERCHANGE) | PSL_VM;
		}
		tf->tf_vm86_ds = scp->sc_ds;
		tf->tf_vm86_es = scp->sc_es;
		tf->tf_vm86_fs = scp->sc_fs;
		tf->tf_vm86_gs = scp->sc_gs;
		tf->tf_ds = _udatasel;
		tf->tf_es = _udatasel;
		tf->tf_fs = _udatasel;
	} else {
		/*
		 * Don't allow users to change privileged or reserved flags.
		 */
		/*
		 * XXX do allow users to change the privileged flag PSL_RF.
		 * The cpu sets PSL_RF in tf_eflags for faults.  Debuggers
		 * should sometimes set it there too.  tf_eflags is kept in
		 * the signal context during signal handling and there is no
		 * other place to remember it, so the PSL_RF bit may be
		 * corrupted by the signal handler without us knowing.
		 * Corruption of the PSL_RF bit at worst causes one more or
		 * one less debugger trap, so allowing it is fairly harmless.
		 */
		if (!EFL_SECURE(eflags & ~PSL_RF, regs->tf_eflags & ~PSL_RF)) {
	    		return (EINVAL);
		}

		/*
		 * Don't allow users to load a valid privileged %cs.  Let the
		 * hardware check for invalid selectors, excess privilege in
		 * other selectors, invalid %eip's and invalid %esp's.
		 */
		if (!CS_SECURE(scp->sc_cs)) {
			trapsignal(td, SIGBUS, T_PROTFLT);
			return (EINVAL);
		}
		regs->tf_ds = scp->sc_ds;
		regs->tf_es = scp->sc_es;
		regs->tf_fs = scp->sc_fs;
	}

	/* Restore remaining registers. */
	regs->tf_eax = scp->sc_eax;
	regs->tf_ebx = scp->sc_ebx;
	regs->tf_ecx = scp->sc_ecx;
	regs->tf_edx = scp->sc_edx;
	regs->tf_esi = scp->sc_esi;
	regs->tf_edi = scp->sc_edi;
	regs->tf_cs = scp->sc_cs;
	regs->tf_ss = scp->sc_ss;
	regs->tf_isp = scp->sc_isp;
	regs->tf_ebp = scp->sc_fp;
	regs->tf_esp = scp->sc_sp;
	regs->tf_eip = scp->sc_pc;
	regs->tf_eflags = eflags;

	PROC_LOCK(p);
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
	if (scp->sc_onstack & 1)
		p->p_sigstk.ss_flags |= SS_ONSTACK;
	else
		p->p_sigstk.ss_flags &= ~SS_ONSTACK;
#endif
	SIGSETOLD(p->p_sigmask, scp->sc_mask);
	SIG_CANTMASK(p->p_sigmask);
	signotify(p);
	PROC_UNLOCK(p);
	return (EJUSTRETURN);
}
#endif /* COMPAT_43 */

#ifdef COMPAT_FREEBSD4
/*
 * MPSAFE
 */
int
freebsd4_sigreturn(td, uap)
	struct thread *td;
	struct freebsd4_sigreturn_args /* {
		const ucontext4 *sigcntxp;
	} */ *uap;
{
	struct ucontext4 uc;
	struct proc *p = td->td_proc;
	struct trapframe *regs;
	const struct ucontext4 *ucp;
	int cs, eflags, error;

	error = copyin(uap->sigcntxp, &uc, sizeof(uc));
	if (error != 0)
		return (error);
	ucp = &uc;
	regs = td->td_frame;
	eflags = ucp->uc_mcontext.mc_eflags;
	if (eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86;

		/*
		 * if pcb_ext == 0 or vm86_inited == 0, the user hasn't
		 * set up the vm86 area, and we can't enter vm86 mode.
		 */
		if (td->td_pcb->pcb_ext == 0)
			return (EINVAL);
		vm86 = &td->td_pcb->pcb_ext->ext_vm86;
		if (vm86->vm86_inited == 0)
			return (EINVAL);

		/* Go back to user mode if both flags are set. */
		if ((eflags & PSL_VIP) && (eflags & PSL_VIF))
			trapsignal(td, SIGBUS, 0);

		if (vm86->vm86_has_vme) {
			eflags = (tf->tf_eflags & ~VME_USERCHANGE) |
			    (eflags & VME_USERCHANGE) | PSL_VM;
		} else {
			vm86->vm86_eflags = eflags;	/* save VIF, VIP */
			eflags = (tf->tf_eflags & ~VM_USERCHANGE) |
			    (eflags & VM_USERCHANGE) | PSL_VM;
		}
		bcopy(&ucp->uc_mcontext.mc_fs, tf, sizeof(struct trapframe));
		tf->tf_eflags = eflags;
		tf->tf_vm86_ds = tf->tf_ds;
		tf->tf_vm86_es = tf->tf_es;
		tf->tf_vm86_fs = tf->tf_fs;
		tf->tf_vm86_gs = ucp->uc_mcontext.mc_gs;
		tf->tf_ds = _udatasel;
		tf->tf_es = _udatasel;
		tf->tf_fs = _udatasel;
	} else {
		/*
		 * Don't allow users to change privileged or reserved flags.
		 */
		/*
		 * XXX do allow users to change the privileged flag PSL_RF.
		 * The cpu sets PSL_RF in tf_eflags for faults.  Debuggers
		 * should sometimes set it there too.  tf_eflags is kept in
		 * the signal context during signal handling and there is no
		 * other place to remember it, so the PSL_RF bit may be
		 * corrupted by the signal handler without us knowing.
		 * Corruption of the PSL_RF bit at worst causes one more or
		 * one less debugger trap, so allowing it is fairly harmless.
		 */
		if (!EFL_SECURE(eflags & ~PSL_RF, regs->tf_eflags & ~PSL_RF)) {
			printf("freebsd4_sigreturn: eflags = 0x%x\n", eflags);
	    		return (EINVAL);
		}

		/*
		 * Don't allow users to load a valid privileged %cs.  Let the
		 * hardware check for invalid selectors, excess privilege in
		 * other selectors, invalid %eip's and invalid %esp's.
		 */
		cs = ucp->uc_mcontext.mc_cs;
		if (!CS_SECURE(cs)) {
			printf("freebsd4_sigreturn: cs = 0x%x\n", cs);
			trapsignal(td, SIGBUS, T_PROTFLT);
			return (EINVAL);
		}

		bcopy(&ucp->uc_mcontext.mc_fs, regs, sizeof(*regs));
	}

	PROC_LOCK(p);
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
	if (ucp->uc_mcontext.mc_onstack & 1)
		p->p_sigstk.ss_flags |= SS_ONSTACK;
	else
		p->p_sigstk.ss_flags &= ~SS_ONSTACK;
#endif

	p->p_sigmask = ucp->uc_sigmask;
	SIG_CANTMASK(p->p_sigmask);
	signotify(p);
	PROC_UNLOCK(p);
	return (EJUSTRETURN);
}
#endif	/* COMPAT_FREEBSD4 */

/*
 * MPSAFE
 */
int
sigreturn(td, uap)
	struct thread *td;
	struct sigreturn_args /* {
		const __ucontext *sigcntxp;
	} */ *uap;
{
	ucontext_t uc;
	struct proc *p = td->td_proc;
	struct trapframe *regs;
	const ucontext_t *ucp;
	int cs, eflags, error, ret;

	error = copyin(uap->sigcntxp, &uc, sizeof(uc));
	if (error != 0)
		return (error);
	ucp = &uc;
	regs = td->td_frame;
	eflags = ucp->uc_mcontext.mc_eflags;
	if (eflags & PSL_VM) {
		struct trapframe_vm86 *tf = (struct trapframe_vm86 *)regs;
		struct vm86_kernel *vm86;

		/*
		 * if pcb_ext == 0 or vm86_inited == 0, the user hasn't
		 * set up the vm86 area, and we can't enter vm86 mode.
		 */
		if (td->td_pcb->pcb_ext == 0)
			return (EINVAL);
		vm86 = &td->td_pcb->pcb_ext->ext_vm86;
		if (vm86->vm86_inited == 0)
			return (EINVAL);

		/* Go back to user mode if both flags are set. */
		if ((eflags & PSL_VIP) && (eflags & PSL_VIF))
			trapsignal(td, SIGBUS, 0);

		if (vm86->vm86_has_vme) {
			eflags = (tf->tf_eflags & ~VME_USERCHANGE) |
			    (eflags & VME_USERCHANGE) | PSL_VM;
		} else {
			vm86->vm86_eflags = eflags;	/* save VIF, VIP */
			eflags = (tf->tf_eflags & ~VM_USERCHANGE) |
			    (eflags & VM_USERCHANGE) | PSL_VM;
		}
		bcopy(&ucp->uc_mcontext.mc_fs, tf, sizeof(struct trapframe));
		tf->tf_eflags = eflags;
		tf->tf_vm86_ds = tf->tf_ds;
		tf->tf_vm86_es = tf->tf_es;
		tf->tf_vm86_fs = tf->tf_fs;
		tf->tf_vm86_gs = ucp->uc_mcontext.mc_gs;
		tf->tf_ds = _udatasel;
		tf->tf_es = _udatasel;
		tf->tf_fs = _udatasel;
	} else {
		/*
		 * Don't allow users to change privileged or reserved flags.
		 */
		/*
		 * XXX do allow users to change the privileged flag PSL_RF.
		 * The cpu sets PSL_RF in tf_eflags for faults.  Debuggers
		 * should sometimes set it there too.  tf_eflags is kept in
		 * the signal context during signal handling and there is no
		 * other place to remember it, so the PSL_RF bit may be
		 * corrupted by the signal handler without us knowing.
		 * Corruption of the PSL_RF bit at worst causes one more or
		 * one less debugger trap, so allowing it is fairly harmless.
		 */
		if (!EFL_SECURE(eflags & ~PSL_RF, regs->tf_eflags & ~PSL_RF)) {
			printf("sigreturn: eflags = 0x%x\n", eflags);
	    		return (EINVAL);
		}

		/*
		 * Don't allow users to load a valid privileged %cs.  Let the
		 * hardware check for invalid selectors, excess privilege in
		 * other selectors, invalid %eip's and invalid %esp's.
		 */
		cs = ucp->uc_mcontext.mc_cs;
		if (!CS_SECURE(cs)) {
			printf("sigreturn: cs = 0x%x\n", cs);
			trapsignal(td, SIGBUS, T_PROTFLT);
			return (EINVAL);
		}

		ret = set_fpcontext(td, &ucp->uc_mcontext);
		if (ret != 0)
			return (ret);
		bcopy(&ucp->uc_mcontext.mc_fs, regs, sizeof(*regs));
	}

	PROC_LOCK(p);
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
	if (ucp->uc_mcontext.mc_onstack & 1)
		p->p_sigstk.ss_flags |= SS_ONSTACK;
	else
		p->p_sigstk.ss_flags &= ~SS_ONSTACK;
#endif

	p->p_sigmask = ucp->uc_sigmask;
	SIG_CANTMASK(p->p_sigmask);
	signotify(p);
	PROC_UNLOCK(p);
	return (EJUSTRETURN);
}

/*
 * Machine dependent boot() routine
 *
 * I haven't seen anything to put here yet
 * Possibly some stuff might be grafted back here from boot()
 */
void
cpu_boot(int howto)
{
}

/*
 * Shutdown the CPU as much as possible
 */
void
cpu_halt(void)
{
	for (;;)
		__asm__ ("hlt");
}

/*
 * Hook to idle the CPU when possible.  In the SMP case we default to
 * off because a halted cpu will not currently pick up a new thread in the
 * run queue until the next timer tick.  If turned on this will result in
 * approximately a 4.2% loss in real time performance in buildworld tests
 * (but improves user and sys times oddly enough), and saves approximately
 * 5% in power consumption on an idle machine (tests w/2xCPU 1.1GHz P3).
 *
 * XXX we need to have a cpu mask of idle cpus and generate an IPI or
 * otherwise generate some sort of interrupt to wake up cpus sitting in HLT.
 * Then we can have our cake and eat it too.
 *
 * XXX I'm turning it on for SMP as well by default for now.  It seems to
 * help lock contention somewhat, and this is critical for HTT. -Peter
 */
static int	cpu_idle_hlt = 1;
SYSCTL_INT(_machdep, OID_AUTO, cpu_idle_hlt, CTLFLAG_RW,
    &cpu_idle_hlt, 0, "Idle loop HLT enable");

/*
 * Note that we have to be careful here to avoid a race between checking
 * sched_runnable() and actually halting.  If we don't do this, we may waste
 * the time between calling hlt and the next interrupt even though there
 * is a runnable process.
 */
void
cpu_idle(void)
{

#ifdef SMP
	if (mp_grab_cpu_hlt())
		return;
#endif

	if (cpu_idle_hlt) {
		disable_intr();
  		if (sched_runnable()) {
			enable_intr();
		} else {
			/*
			 * we must absolutely guarentee that hlt is the
			 * absolute next instruction after sti or we
			 * introduce a timing window.
			 */
			__asm __volatile("sti; hlt");
		}
	}
}

/*
 * Clear registers on exec
 */
void
exec_setregs(td, entry, stack, ps_strings)
	struct thread *td;
	u_long entry;
	u_long stack;
	u_long ps_strings;
{
	struct trapframe *regs = td->td_frame;
	struct pcb *pcb = td->td_pcb;

	/* Reset pc->pcb_gs and %gs before possibly invalidating it. */
	pcb->pcb_gs = _udatasel;
	load_gs(_udatasel);

	if (td->td_proc->p_md.md_ldt)
		user_ldt_free(td);

	bzero((char *)regs, sizeof(struct trapframe));
	regs->tf_eip = entry;
	regs->tf_esp = stack;
	regs->tf_eflags = PSL_USER | (regs->tf_eflags & PSL_T);
	regs->tf_ss = _udatasel;
	regs->tf_ds = _udatasel;
	regs->tf_es = _udatasel;
	regs->tf_fs = _udatasel;
	regs->tf_cs = _ucodesel;

	/* PS_STRINGS value for BSD/OS binaries.  It is 0 for non-BSD/OS. */
	regs->tf_ebx = ps_strings;

        /*
         * Reset the hardware debug registers if they were in use.
         * They won't have any meaning for the newly exec'd process.
         */
        if (pcb->pcb_flags & PCB_DBREGS) {
                pcb->pcb_dr0 = 0;
                pcb->pcb_dr1 = 0;
                pcb->pcb_dr2 = 0;
                pcb->pcb_dr3 = 0;
                pcb->pcb_dr6 = 0;
                pcb->pcb_dr7 = 0;
                if (pcb == PCPU_GET(curpcb)) {
		        /*
			 * Clear the debug registers on the running
			 * CPU, otherwise they will end up affecting
			 * the next process we switch to.
			 */
		        reset_dbregs();
                }
                pcb->pcb_flags &= ~PCB_DBREGS;
        }

	/*
	 * Initialize the math emulator (if any) for the current process.
	 * Actually, just clear the bit that says that the emulator has
	 * been initialized.  Initialization is delayed until the process
	 * traps to the emulator (if it is done at all) mainly because
	 * emulators don't provide an entry point for initialization.
	 */
	td->td_pcb->pcb_flags &= ~FP_SOFTFP;

	/*
	 * Arrange to trap the next npx or `fwait' instruction (see npx.c
	 * for why fwait must be trapped at least if there is an npx or an
	 * emulator).  This is mainly to handle the case where npx0 is not
	 * configured, since the npx routines normally set up the trap
	 * otherwise.  It should be done only at boot time, but doing it
	 * here allows modifying `npx_exists' for testing the emulator on
	 * systems with an npx.
	 */
	load_cr0(rcr0() | CR0_MP | CR0_TS);

	/* Initialize the npx (if any) for the current process. */
	/*
	 * XXX the above load_cr0() also initializes it and is a layering
	 * violation if NPX is configured.  It drops the npx partially
	 * and this would be fatal if we were interrupted now, and decided
	 * to force the state to the pcb, and checked the invariant
	 * (CR0_TS clear) if and only if PCPU_GET(fpcurthread) != NULL).
	 * ALL of this can happen except the check.  The check used to
	 * happen and be fatal later when we didn't complete the drop
	 * before returning to user mode.  This should be fixed properly
	 * soon.
	 */
	fpstate_drop(td);

	/*
	 * XXX - Linux emulator
	 * Make sure sure edx is 0x0 on entry. Linux binaries depend
	 * on it.
	 */
	td->td_retval[1] = 0;
}

void
cpu_setregs(void)
{
	unsigned int cr0;

	cr0 = rcr0();
#ifdef SMP
	cr0 |= CR0_NE;			/* Done by npxinit() */
#endif
	cr0 |= CR0_MP | CR0_TS;		/* Done at every execve() too. */
#ifndef I386_CPU
	cr0 |= CR0_WP | CR0_AM;
#endif
	load_cr0(cr0);
	load_gs(_udatasel);
}

static int
sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
{
	int error;
	error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
		req);
	if (!error && req->newptr)
		resettodr();
	return (error);
}

SYSCTL_PROC(_machdep, CPU_ADJKERNTZ, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
	&adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");

SYSCTL_INT(_machdep, CPU_DISRTCSET, disable_rtc_set,
	CTLFLAG_RW, &disable_rtc_set, 0, "");

SYSCTL_STRUCT(_machdep, CPU_BOOTINFO, bootinfo,
	CTLFLAG_RD, &bootinfo, bootinfo, "");

SYSCTL_INT(_machdep, CPU_WALLCLOCK, wall_cmos_clock,
	CTLFLAG_RW, &wall_cmos_clock, 0, "");

u_long bootdev;		/* not a dev_t - encoding is different */
SYSCTL_ULONG(_machdep, OID_AUTO, guessed_bootdev,
	CTLFLAG_RD, &bootdev, 0, "Maybe the Boot device (not in dev_t format)");

/*
 * Initialize 386 and configure to run kernel
 */

/*
 * Initialize segments & interrupt table
 */

int _default_ldt;
union descriptor gdt[NGDT * MAXCPU];	/* global descriptor table */
static struct gate_descriptor idt0[NIDT];
struct gate_descriptor *idt = &idt0[0];	/* interrupt descriptor table */
union descriptor ldt[NLDT];		/* local descriptor table */
#ifdef SMP
/* table descriptors - used to load tables by microp */
struct region_descriptor r_gdt, r_idt;
#endif

int private_tss;			/* flag indicating private tss */

#if defined(I586_CPU) && !defined(NO_F00F_HACK)
extern int has_f00f_bug;
#endif

static struct i386tss dblfault_tss;
static char dblfault_stack[PAGE_SIZE];

extern  struct user	*proc0uarea;
extern  vm_offset_t	proc0kstack;


/* software prototypes -- in more palatable form */
struct soft_segment_descriptor gdt_segs[] = {
/* GNULL_SEL	0 Null Descriptor */
{	0x0,			/* segment base address  */
	0x0,			/* length */
	0,			/* segment type */
	0,			/* segment descriptor priority level */
	0,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
/* GCODE_SEL	1 Code Descriptor for kernel */
{	0x0,			/* segment base address  */
	0xfffff,		/* length - all address space */
	SDT_MEMERA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	1,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GDATA_SEL	2 Data Descriptor for kernel */
{	0x0,			/* segment base address  */
	0xfffff,		/* length - all address space */
	SDT_MEMRWA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	1,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GPRIV_SEL	3 SMP Per-Processor Private Data Descriptor */
{	0x0,			/* segment base address  */
	0xfffff,		/* length - all address space */
	SDT_MEMRWA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	1,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GPROC0_SEL	4 Proc 0 Tss Descriptor */
{
	0x0,			/* segment base address */
	sizeof(struct i386tss)-1,/* length - all address space */
	SDT_SYS386TSS,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* unused - default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
/* GLDT_SEL	5 LDT Descriptor */
{	(int) ldt,		/* segment base address  */
	sizeof(ldt)-1,		/* length - all address space */
	SDT_SYSLDT,		/* segment type */
	SEL_UPL,		/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* unused - default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
/* GUSERLDT_SEL	6 User LDT Descriptor per process */
{	(int) ldt,		/* segment base address  */
	(512 * sizeof(union descriptor)-1),		/* length */
	SDT_SYSLDT,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* unused - default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
/* GTGATE_SEL	7 Null Descriptor - Placeholder */
{	0x0,			/* segment base address  */
	0x0,			/* length - all address space */
	0,			/* segment type */
	0,			/* segment descriptor priority level */
	0,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
/* GBIOSLOWMEM_SEL 8 BIOS access to realmode segment 0x40, must be #8 in GDT */
{	0x400,			/* segment base address */
	0xfffff,		/* length */
	SDT_MEMRWA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	1,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GPANIC_SEL	9 Panic Tss Descriptor */
{	(int) &dblfault_tss,	/* segment base address  */
	sizeof(struct i386tss)-1,/* length - all address space */
	SDT_SYS386TSS,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* unused - default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
/* GBIOSCODE32_SEL 10 BIOS 32-bit interface (32bit Code) */
{	0,			/* segment base address (overwritten)  */
	0xfffff,		/* length */
	SDT_MEMERA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GBIOSCODE16_SEL 11 BIOS 32-bit interface (16bit Code) */
{	0,			/* segment base address (overwritten)  */
	0xfffff,		/* length */
	SDT_MEMERA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GBIOSDATA_SEL 12 BIOS 32-bit interface (Data) */
{	0,			/* segment base address (overwritten) */
	0xfffff,		/* length */
	SDT_MEMRWA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	1,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GBIOSUTIL_SEL 13 BIOS 16-bit interface (Utility) */
{	0,			/* segment base address (overwritten) */
	0xfffff,		/* length */
	SDT_MEMRWA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
/* GBIOSARGS_SEL 14 BIOS 16-bit interface (Arguments) */
{	0,			/* segment base address (overwritten) */
	0xfffff,		/* length */
	SDT_MEMRWA,		/* segment type */
	0,			/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
};

static struct soft_segment_descriptor ldt_segs[] = {
	/* Null Descriptor - overwritten by call gate */
{	0x0,			/* segment base address  */
	0x0,			/* length - all address space */
	0,			/* segment type */
	0,			/* segment descriptor priority level */
	0,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
	/* Null Descriptor - overwritten by call gate */
{	0x0,			/* segment base address  */
	0x0,			/* length - all address space */
	0,			/* segment type */
	0,			/* segment descriptor priority level */
	0,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
	/* Null Descriptor - overwritten by call gate */
{	0x0,			/* segment base address  */
	0x0,			/* length - all address space */
	0,			/* segment type */
	0,			/* segment descriptor priority level */
	0,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
	/* Code Descriptor for user */
{	0x0,			/* segment base address  */
	0xfffff,		/* length - all address space */
	SDT_MEMERA,		/* segment type */
	SEL_UPL,		/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	1,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
	/* Null Descriptor - overwritten by call gate */
{	0x0,			/* segment base address  */
	0x0,			/* length - all address space */
	0,			/* segment type */
	0,			/* segment descriptor priority level */
	0,			/* segment descriptor present */
	0, 0,
	0,			/* default 32 vs 16 bit size */
	0  			/* limit granularity (byte/page units)*/ },
	/* Data Descriptor for user */
{	0x0,			/* segment base address  */
	0xfffff,		/* length - all address space */
	SDT_MEMRWA,		/* segment type */
	SEL_UPL,		/* segment descriptor priority level */
	1,			/* segment descriptor present */
	0, 0,
	1,			/* default 32 vs 16 bit size */
	1  			/* limit granularity (byte/page units)*/ },
};

void
setidt(idx, func, typ, dpl, selec)
	int idx;
	inthand_t *func;
	int typ;
	int dpl;
	int selec;
{
	struct gate_descriptor *ip;

	ip = idt + idx;
	ip->gd_looffset = (int)func;
	ip->gd_selector = selec;
	ip->gd_stkcpy = 0;
	ip->gd_xx = 0;
	ip->gd_type = typ;
	ip->gd_dpl = dpl;
	ip->gd_p = 1;
	ip->gd_hioffset = ((int)func)>>16 ;
}

#define	IDTVEC(name)	__CONCAT(X,name)

extern inthand_t
	IDTVEC(div), IDTVEC(dbg), IDTVEC(nmi), IDTVEC(bpt), IDTVEC(ofl),
	IDTVEC(bnd), IDTVEC(ill), IDTVEC(dna), IDTVEC(fpusegm),
	IDTVEC(tss), IDTVEC(missing), IDTVEC(stk), IDTVEC(prot),
	IDTVEC(page), IDTVEC(mchk), IDTVEC(rsvd), IDTVEC(fpu), IDTVEC(align),
	IDTVEC(xmm), IDTVEC(lcall_syscall), IDTVEC(int0x80_syscall);

void
sdtossd(sd, ssd)
	struct segment_descriptor *sd;
	struct soft_segment_descriptor *ssd;
{
	ssd->ssd_base  = (sd->sd_hibase << 24) | sd->sd_lobase;
	ssd->ssd_limit = (sd->sd_hilimit << 16) | sd->sd_lolimit;
	ssd->ssd_type  = sd->sd_type;
	ssd->ssd_dpl   = sd->sd_dpl;
	ssd->ssd_p     = sd->sd_p;
	ssd->ssd_def32 = sd->sd_def32;
	ssd->ssd_gran  = sd->sd_gran;
}

#define PHYSMAP_SIZE	(2 * 8)

/*
 * Populate the (physmap) array with base/bound pairs describing the
 * available physical memory in the system, then test this memory and
 * build the phys_avail array describing the actually-available memory.
 *
 * If we cannot accurately determine the physical memory map, then use
 * value from the 0xE801 call, and failing that, the RTC.
 *
 * Total memory size may be set by the kernel environment variable
 * hw.physmem or the compile-time define MAXMEM.
 *
 * XXX first should be vm_paddr_t.
 */
static void
getmemsize(int first)
{
	int i, physmap_idx, pa_indx;
	int hasbrokenint12;
	u_int basemem, extmem;
	struct vm86frame vmf;
	struct vm86context vmc;
	vm_paddr_t pa, physmap[PHYSMAP_SIZE];
	pt_entry_t *pte;
	char *cp;
	struct bios_smap *smap;

	hasbrokenint12 = 0;
	TUNABLE_INT_FETCH("hw.hasbrokenint12", &hasbrokenint12);
	bzero(&vmf, sizeof(struct vm86frame));
	bzero(physmap, sizeof(physmap));
	basemem = 0;

	/*
	 * Some newer BIOSes has broken INT 12H implementation which cause
	 * kernel panic immediately. In this case, we need to scan SMAP
	 * with INT 15:E820 first, then determine base memory size.
	 */
	if (hasbrokenint12) {
		goto int15e820;
	}

	/*
	 * Perform "base memory" related probes & setup
	 */
	vm86_intcall(0x12, &vmf);
	basemem = vmf.vmf_ax;
	if (basemem > 640) {
		printf("Preposterous BIOS basemem of %uK, truncating to 640K\n",
			basemem);
		basemem = 640;
	}

	/*
	 * XXX if biosbasemem is now < 640, there is a `hole'
	 * between the end of base memory and the start of
	 * ISA memory.  The hole may be empty or it may
	 * contain BIOS code or data.  Map it read/write so
	 * that the BIOS can write to it.  (Memory from 0 to
	 * the physical end of the kernel is mapped read-only
	 * to begin with and then parts of it are remapped.
	 * The parts that aren't remapped form holes that
	 * remain read-only and are unused by the kernel.
	 * The base memory area is below the physical end of
	 * the kernel and right now forms a read-only hole.
	 * The part of it from PAGE_SIZE to
	 * (trunc_page(biosbasemem * 1024) - 1) will be
	 * remapped and used by the kernel later.)
	 *
	 * This code is similar to the code used in
	 * pmap_mapdev, but since no memory needs to be
	 * allocated we simply change the mapping.
	 */
	for (pa = trunc_page(basemem * 1024);
	     pa < ISA_HOLE_START; pa += PAGE_SIZE)
		pmap_kenter(KERNBASE + pa, pa);

	/*
	 * if basemem != 640, map pages r/w into vm86 page table so
	 * that the bios can scribble on it.
	 */
	pte = (pt_entry_t *)vm86paddr;
	for (i = basemem / 4; i < 160; i++)
		pte[i] = (i << PAGE_SHIFT) | PG_V | PG_RW | PG_U;

int15e820:
	/*
	 * map page 1 R/W into the kernel page table so we can use it
	 * as a buffer.  The kernel will unmap this page later.
	 */
	pmap_kenter(KERNBASE + (1 << PAGE_SHIFT), 1 << PAGE_SHIFT);

	/*
	 * get memory map with INT 15:E820
	 */
	vmc.npages = 0;
	smap = (void *)vm86_addpage(&vmc, 1, KERNBASE + (1 << PAGE_SHIFT));
	vm86_getptr(&vmc, (vm_offset_t)smap, &vmf.vmf_es, &vmf.vmf_di);

	physmap_idx = 0;
	vmf.vmf_ebx = 0;
	do {
		vmf.vmf_eax = 0xE820;
		vmf.vmf_edx = SMAP_SIG;
		vmf.vmf_ecx = sizeof(struct bios_smap);
		i = vm86_datacall(0x15, &vmf, &vmc);
		if (i || vmf.vmf_eax != SMAP_SIG)
			break;
		if (boothowto & RB_VERBOSE)
			printf("SMAP type=%02x base=%016llx len=%016llx\n",
			    smap->type, smap->base, smap->length);

		if (smap->type != 0x01)
			goto next_run;

		if (smap->length == 0)
			goto next_run;

#ifndef PAE
		if (smap->base >= 0xffffffff) {
			printf("%uK of memory above 4GB ignored\n",
			    (u_int)(smap->length / 1024));
			goto next_run;
		}
#endif

		for (i = 0; i <= physmap_idx; i += 2) {
			if (smap->base < physmap[i + 1]) {
				if (boothowto & RB_VERBOSE)
					printf(
	"Overlapping or non-montonic memory region, ignoring second region\n");
				goto next_run;
			}
		}

		if (smap->base == physmap[physmap_idx + 1]) {
			physmap[physmap_idx + 1] += smap->length;
			goto next_run;
		}

		physmap_idx += 2;
		if (physmap_idx == PHYSMAP_SIZE) {
			printf(
		"Too many segments in the physical address map, giving up\n");
			break;
		}
		physmap[physmap_idx] = smap->base;
		physmap[physmap_idx + 1] = smap->base + smap->length;
next_run: ;
	} while (vmf.vmf_ebx != 0);

	/*
	 * Perform "base memory" related probes & setup based on SMAP
	 */
	if (basemem == 0) {
		for (i = 0; i <= physmap_idx; i += 2) {
			if (physmap[i] == 0x00000000) {
				basemem = physmap[i + 1] / 1024;
				break;
			}
		}

		if (basemem == 0) {
			basemem = 640;
		}

		if (basemem > 640) {
			printf("Preposterous BIOS basemem of %uK, truncating to 640K\n",
				basemem);
			basemem = 640;
		}

		for (pa = trunc_page(basemem * 1024);
		     pa < ISA_HOLE_START; pa += PAGE_SIZE)
			pmap_kenter(KERNBASE + pa, pa);

		pte = (pt_entry_t *)vm86paddr;
		for (i = basemem / 4; i < 160; i++)
			pte[i] = (i << PAGE_SHIFT) | PG_V | PG_RW | PG_U;
	}

	if (physmap[1] != 0)
		goto physmap_done;

	/*
	 * If we failed above, try memory map with INT 15:E801
	 */
	vmf.vmf_ax = 0xE801;
	if (vm86_intcall(0x15, &vmf) == 0) {
		extmem = vmf.vmf_cx + vmf.vmf_dx * 64;
	} else {
#if 0
		vmf.vmf_ah = 0x88;
		vm86_intcall(0x15, &vmf);
		extmem = vmf.vmf_ax;
#else
		/*
		 * Prefer the RTC value for extended memory.
		 */
		extmem = rtcin(RTC_EXTLO) + (rtcin(RTC_EXTHI) << 8);
#endif
	}

	/*
	 * Special hack for chipsets that still remap the 384k hole when
	 * there's 16MB of memory - this really confuses people that
	 * are trying to use bus mastering ISA controllers with the
	 * "16MB limit"; they only have 16MB, but the remapping puts
	 * them beyond the limit.
	 *
	 * If extended memory is between 15-16MB (16-17MB phys address range),
	 *	chop it to 15MB.
	 */
	if ((extmem > 15 * 1024) && (extmem < 16 * 1024))
		extmem = 15 * 1024;

	physmap[0] = 0;
	physmap[1] = basemem * 1024;
	physmap_idx = 2;
	physmap[physmap_idx] = 0x100000;
	physmap[physmap_idx + 1] = physmap[physmap_idx] + extmem * 1024;

physmap_done:
	/*
	 * Now, physmap contains a map of physical memory.
	 */

#ifdef SMP
	/* make hole for AP bootstrap code */
	physmap[1] = mp_bootaddress(physmap[1] / 1024);

	/* look for the MP hardware - needed for apic addresses */
	i386_mp_probe();
#endif

	/*
	 * Maxmem isn't the "maximum memory", it's one larger than the
	 * highest page of the physical address space.  It should be
	 * called something like "Maxphyspage".  We may adjust this
	 * based on ``hw.physmem'' and the results of the memory test.
	 */
	Maxmem = atop(physmap[physmap_idx + 1]);

#ifdef MAXMEM
	Maxmem = MAXMEM / 4;
#endif

	/*
	 * hw.physmem is a size in bytes; we also allow k, m, and g suffixes
	 * for the appropriate modifiers.  This overrides MAXMEM.
	 */
	if ((cp = getenv("hw.physmem")) != NULL) {
		u_int64_t AllowMem, sanity;
		char *ep;

		sanity = AllowMem = strtouq(cp, &ep, 0);
		if ((ep != cp) && (*ep != 0)) {
			switch(*ep) {
			case 'g':
			case 'G':
				AllowMem <<= 10;
			case 'm':
			case 'M':
				AllowMem <<= 10;
			case 'k':
			case 'K':
				AllowMem <<= 10;
				break;
			default:
				AllowMem = sanity = 0;
			}
			if (AllowMem < sanity)
				AllowMem = 0;
		}
		if (AllowMem == 0)
			printf("Ignoring invalid memory size of '%s'\n", cp);
		else
			Maxmem = atop(AllowMem);
		freeenv(cp);
	}

	if (atop(physmap[physmap_idx + 1]) != Maxmem &&
	    (boothowto & RB_VERBOSE))
		printf("Physical memory use set to %ldK\n", Maxmem * 4);

	/*
	 * If Maxmem has been increased beyond what the system has detected,
	 * extend the last memory segment to the new limit.
	 */
	if (atop(physmap[physmap_idx + 1]) < Maxmem)
		physmap[physmap_idx + 1] = ptoa((vm_paddr_t)Maxmem);

	/* call pmap initialization to make new kernel address space */
	pmap_bootstrap(first, 0);

	/*
	 * Size up each available chunk of physical memory.
	 */
	physmap[0] = PAGE_SIZE;		/* mask off page 0 */
	pa_indx = 0;
	phys_avail[pa_indx++] = physmap[0];
	phys_avail[pa_indx] = physmap[0];
	pte = CMAP1;

	/*
	 * physmap is in bytes, so when converting to page boundaries,
	 * round up the start address and round down the end address.
	 */
	for (i = 0; i <= physmap_idx; i += 2) {
		vm_paddr_t end;

		end = ptoa((vm_paddr_t)Maxmem);
		if (physmap[i + 1] < end)
			end = trunc_page(physmap[i + 1]);
		for (pa = round_page(physmap[i]); pa < end; pa += PAGE_SIZE) {
			int tmp, page_bad;
			int *ptr = (int *)CADDR1;

			/*
			 * block out kernel memory as not available.
			 */
			if (pa >= 0x100000 && pa < first)
				continue;

			page_bad = FALSE;

			/*
			 * map page into kernel: valid, read/write,non-cacheable
			 */
			*pte = pa | PG_V | PG_RW | PG_N;
			invltlb();

			tmp = *(int *)ptr;
			/*
			 * Test for alternating 1's and 0's
			 */
			*(volatile int *)ptr = 0xaaaaaaaa;
			if (*(volatile int *)ptr != 0xaaaaaaaa) {
				page_bad = TRUE;
			}
			/*
			 * Test for alternating 0's and 1's
			 */
			*(volatile int *)ptr = 0x55555555;
			if (*(volatile int *)ptr != 0x55555555) {
			page_bad = TRUE;
			}
			/*
			 * Test for all 1's
			 */
			*(volatile int *)ptr = 0xffffffff;
			if (*(volatile int *)ptr != 0xffffffff) {
				page_bad = TRUE;
			}
			/*
			 * Test for all 0's
			 */
			*(volatile int *)ptr = 0x0;
			if (*(volatile int *)ptr != 0x0) {
				page_bad = TRUE;
			}
			/*
			 * Restore original value.
			 */
			*(int *)ptr = tmp;

			/*
			 * Adjust array of valid/good pages.
			 */
			if (page_bad == TRUE) {
				continue;
			}
			/*
			 * If this good page is a continuation of the
			 * previous set of good pages, then just increase
			 * the end pointer. Otherwise start a new chunk.
			 * Note that "end" points one higher than end,
			 * making the range >= start and < end.
			 * If we're also doing a speculative memory
			 * test and we at or past the end, bump up Maxmem
			 * so that we keep going. The first bad page
			 * will terminate the loop.
			 */
			if (phys_avail[pa_indx] == pa) {
				phys_avail[pa_indx] += PAGE_SIZE;
			} else {
				pa_indx++;
				if (pa_indx == PHYS_AVAIL_ARRAY_END) {
					printf(
		"Too many holes in the physical address space, giving up\n");
					pa_indx--;
					break;
				}
				phys_avail[pa_indx++] = pa;	/* start */
				phys_avail[pa_indx] = pa + PAGE_SIZE;	/* end */
			}
			physmem++;
		}
	}
	*pte = 0;
	invltlb();

	/*
	 * XXX
	 * The last chunk must contain at least one page plus the message
	 * buffer to avoid complicating other code (message buffer address
	 * calculation, etc.).
	 */
	while (phys_avail[pa_indx - 1] + PAGE_SIZE +
	    round_page(MSGBUF_SIZE) >= phys_avail[pa_indx]) {
		physmem -= atop(phys_avail[pa_indx] - phys_avail[pa_indx - 1]);
		phys_avail[pa_indx--] = 0;
		phys_avail[pa_indx--] = 0;
	}

	Maxmem = atop(phys_avail[pa_indx]);

	/* Trim off space for the message buffer. */
	phys_avail[pa_indx] -= round_page(MSGBUF_SIZE);

	avail_end = phys_avail[pa_indx];
}

void
init386(first)
	int first;
{
	struct gate_descriptor *gdp;
	int gsel_tss, metadata_missing, off, x;
#ifndef SMP
	/* table descriptors - used to load tables by microp */
	struct region_descriptor r_gdt, r_idt;
#endif
	struct pcpu *pc;

	proc0.p_uarea = proc0uarea;
	thread0.td_kstack = proc0kstack;
	thread0.td_pcb = (struct pcb *)
	   (thread0.td_kstack + KSTACK_PAGES * PAGE_SIZE) - 1;
	atdevbase = ISA_HOLE_START + KERNBASE;

	/*
 	 * This may be done better later if it gets more high level
 	 * components in it. If so just link td->td_proc here.
	 */
	proc_linkup(&proc0, &ksegrp0, &kse0, &thread0);

	metadata_missing = 0;
	if (bootinfo.bi_modulep) {
		preload_metadata = (caddr_t)bootinfo.bi_modulep + KERNBASE;
		preload_bootstrap_relocate(KERNBASE);
	} else {
		metadata_missing = 1;
	}
	if (envmode == 1)
		kern_envp = static_env;
	else if (bootinfo.bi_envp)
		kern_envp = (caddr_t)bootinfo.bi_envp + KERNBASE;

	/* Init basic tunables, hz etc */
	init_param1();

	/*
	 * make gdt memory segments, the code segment goes up to end of the
	 * page with etext in it, the data segment goes to the end of
	 * the address space
	 */
	/*
	 * XXX text protection is temporarily (?) disabled.  The limit was
	 * i386_btop(round_page(etext)) - 1.
	 */
	gdt_segs[GCODE_SEL].ssd_limit = atop(0 - 1);
	gdt_segs[GDATA_SEL].ssd_limit = atop(0 - 1);
#ifdef SMP
	pc = &SMP_prvspace[0].pcpu;
	gdt_segs[GPRIV_SEL].ssd_limit =
		atop(sizeof(struct privatespace) - 1);
#else
	pc = &__pcpu;
	gdt_segs[GPRIV_SEL].ssd_limit =
		atop(sizeof(struct pcpu) - 1);
#endif
	gdt_segs[GPRIV_SEL].ssd_base = (int) pc;
	gdt_segs[GPROC0_SEL].ssd_base = (int) &pc->pc_common_tss;

	for (x = 0; x < NGDT; x++)
		ssdtosd(&gdt_segs[x], &gdt[x].sd);

	r_gdt.rd_limit = NGDT * sizeof(gdt[0]) - 1;
	r_gdt.rd_base =  (int) gdt;
	lgdt(&r_gdt);

	pcpu_init(pc, 0, sizeof(struct pcpu));
	PCPU_SET(prvspace, pc);
	PCPU_SET(curthread, &thread0);

	/*
	 * Initialize mutexes.
	 *
	 * icu_lock: in order to allow an interrupt to occur in a critical
	 * 	     section, to set pcpu->ipending (etc...) properly, we
	 *	     must be able to get the icu lock, so it can't be
	 *	     under witness.
	 */
	mutex_init();
	mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_RECURSE);
	mtx_init(&icu_lock, "icu", NULL, MTX_SPIN | MTX_NOWITNESS);

	/* make ldt memory segments */
	/*
	 * XXX - VM_MAXUSER_ADDRESS is an end address, not a max.  And it
	 * should be spelled ...MAX_USER...
	 */
	ldt_segs[LUCODE_SEL].ssd_limit = atop(VM_MAXUSER_ADDRESS - 1);
	ldt_segs[LUDATA_SEL].ssd_limit = atop(VM_MAXUSER_ADDRESS - 1);
	for (x = 0; x < sizeof ldt_segs / sizeof ldt_segs[0]; x++)
		ssdtosd(&ldt_segs[x], &ldt[x].sd);

	_default_ldt = GSEL(GLDT_SEL, SEL_KPL);
	lldt(_default_ldt);
	PCPU_SET(currentldt, _default_ldt);

	/* exceptions */
	for (x = 0; x < NIDT; x++)
		setidt(x, &IDTVEC(rsvd), SDT_SYS386TGT, SEL_KPL,
		    GSEL(GCODE_SEL, SEL_KPL));
	setidt(0, &IDTVEC(div),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(1, &IDTVEC(dbg),  SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(2, &IDTVEC(nmi),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
 	setidt(3, &IDTVEC(bpt),  SDT_SYS386IGT, SEL_UPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(4, &IDTVEC(ofl),  SDT_SYS386TGT, SEL_UPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(5, &IDTVEC(bnd),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(6, &IDTVEC(ill),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(7, &IDTVEC(dna),  SDT_SYS386TGT, SEL_KPL
	    , GSEL(GCODE_SEL, SEL_KPL));
	setidt(8, 0,  SDT_SYSTASKGT, SEL_KPL, GSEL(GPANIC_SEL, SEL_KPL));
	setidt(9, &IDTVEC(fpusegm),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(10, &IDTVEC(tss),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(11, &IDTVEC(missing),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(12, &IDTVEC(stk),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(13, &IDTVEC(prot),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(14, &IDTVEC(page),  SDT_SYS386IGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(15, &IDTVEC(rsvd),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(16, &IDTVEC(fpu),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(17, &IDTVEC(align), SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(18, &IDTVEC(mchk),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(19, &IDTVEC(xmm), SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
 	setidt(0x80, &IDTVEC(int0x80_syscall), SDT_SYS386TGT, SEL_UPL,
	    GSEL(GCODE_SEL, SEL_KPL));

	r_idt.rd_limit = sizeof(idt0) - 1;
	r_idt.rd_base = (int) idt;
	lidt(&r_idt);

	/*
	 * Initialize the console before we print anything out.
	 */
	cninit();

	if (metadata_missing)
		printf("WARNING: loader(8) metadata is missing!\n");

#ifdef DEV_ISA
	isa_defaultirq();
#endif

#ifdef DDB
	kdb_init();
	if (boothowto & RB_KDB)
		Debugger("Boot flags requested debugger");
#endif

	finishidentcpu();	/* Final stage of CPU initialization */
	setidt(6, &IDTVEC(ill),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	setidt(13, &IDTVEC(prot),  SDT_SYS386TGT, SEL_KPL,
	    GSEL(GCODE_SEL, SEL_KPL));
	initializecpu();	/* Initialize CPU registers */

	/* make an initial tss so cpu can get interrupt stack on syscall! */
	/* Note: -16 is so we can grow the trapframe if we came from vm86 */
	PCPU_SET(common_tss.tss_esp0, thread0.td_kstack +
	    KSTACK_PAGES * PAGE_SIZE - sizeof(struct pcb) - 16);
	PCPU_SET(common_tss.tss_ss0, GSEL(GDATA_SEL, SEL_KPL));
	gsel_tss = GSEL(GPROC0_SEL, SEL_KPL);
	private_tss = 0;
	PCPU_SET(tss_gdt, &gdt[GPROC0_SEL].sd);
	PCPU_SET(common_tssd, *PCPU_GET(tss_gdt));
	PCPU_SET(common_tss.tss_ioopt, (sizeof (struct i386tss)) << 16);
	ltr(gsel_tss);

	dblfault_tss.tss_esp = dblfault_tss.tss_esp0 = dblfault_tss.tss_esp1 =
	    dblfault_tss.tss_esp2 = (int)&dblfault_stack[sizeof(dblfault_stack)];
	dblfault_tss.tss_ss = dblfault_tss.tss_ss0 = dblfault_tss.tss_ss1 =
	    dblfault_tss.tss_ss2 = GSEL(GDATA_SEL, SEL_KPL);
#ifdef PAE
	dblfault_tss.tss_cr3 = (int)IdlePDPT;
#else
	dblfault_tss.tss_cr3 = (int)IdlePTD;
#endif
	dblfault_tss.tss_eip = (int)dblfault_handler;
	dblfault_tss.tss_eflags = PSL_KERNEL;
	dblfault_tss.tss_ds = dblfault_tss.tss_es =
	    dblfault_tss.tss_gs = GSEL(GDATA_SEL, SEL_KPL);
	dblfault_tss.tss_fs = GSEL(GPRIV_SEL, SEL_KPL);
	dblfault_tss.tss_cs = GSEL(GCODE_SEL, SEL_KPL);
	dblfault_tss.tss_ldt = GSEL(GLDT_SEL, SEL_KPL);

	vm86_initialize();
	getmemsize(first);
	init_param2(physmem);

	/* now running on new page tables, configured,and u/iom is accessible */

	/* Map the message buffer. */
	for (off = 0; off < round_page(MSGBUF_SIZE); off += PAGE_SIZE)
		pmap_kenter((vm_offset_t)msgbufp + off, avail_end + off);

	msgbufinit(msgbufp, MSGBUF_SIZE);

	/* make a call gate to reenter kernel with */
	gdp = &ldt[LSYS5CALLS_SEL].gd;

	x = (int) &IDTVEC(lcall_syscall);
	gdp->gd_looffset = x;
	gdp->gd_selector = GSEL(GCODE_SEL,SEL_KPL);
	gdp->gd_stkcpy = 1;
	gdp->gd_type = SDT_SYS386CGT;
	gdp->gd_dpl = SEL_UPL;
	gdp->gd_p = 1;
	gdp->gd_hioffset = x >> 16;

	/* XXX does this work? */
	ldt[LBSDICALLS_SEL] = ldt[LSYS5CALLS_SEL];
	ldt[LSOL26CALLS_SEL] = ldt[LSYS5CALLS_SEL];

	/* transfer to user mode */

	_ucodesel = LSEL(LUCODE_SEL, SEL_UPL);
	_udatasel = LSEL(LUDATA_SEL, SEL_UPL);

	/* setup proc 0's pcb */
	thread0.td_pcb->pcb_flags = 0; /* XXXKSE */
#ifdef PAE
	thread0.td_pcb->pcb_cr3 = (int)IdlePDPT;
#else
	thread0.td_pcb->pcb_cr3 = (int)IdlePTD;
#endif
	thread0.td_pcb->pcb_ext = 0;
	thread0.td_frame = &proc0_tf;
}

void
cpu_pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
{
}

#if defined(I586_CPU) && !defined(NO_F00F_HACK)
static void f00f_hack(void *unused);
SYSINIT(f00f_hack, SI_SUB_INTRINSIC, SI_ORDER_FIRST, f00f_hack, NULL);

static void
f00f_hack(void *unused) {
	struct gate_descriptor *new_idt;
#ifndef SMP
	struct region_descriptor r_idt;
#endif
	vm_offset_t tmp;

	if (!has_f00f_bug)
		return;

	GIANT_REQUIRED;

	printf("Intel Pentium detected, installing workaround for F00F bug\n");

	r_idt.rd_limit = sizeof(idt0) - 1;

	tmp = kmem_alloc(kernel_map, PAGE_SIZE * 2);
	if (tmp == 0)
		panic("kmem_alloc returned 0");
	if (((unsigned int)tmp & (PAGE_SIZE-1)) != 0)
		panic("kmem_alloc returned non-page-aligned memory");
	/* Put the first seven entries in the lower page */
	new_idt = (struct gate_descriptor*)(tmp + PAGE_SIZE - (7*8));
	bcopy(idt, new_idt, sizeof(idt0));
	r_idt.rd_base = (int)new_idt;
	lidt(&r_idt);
	idt = new_idt;
	if (vm_map_protect(kernel_map, tmp, tmp + PAGE_SIZE,
			   VM_PROT_READ, FALSE) != KERN_SUCCESS)
		panic("vm_map_protect failed");
	return;
}
#endif /* defined(I586_CPU) && !NO_F00F_HACK */

int
ptrace_set_pc(struct thread *td, unsigned long addr)
{
	td->td_frame->tf_eip = addr;
	return (0);
}

int
ptrace_single_step(struct thread *td)
{
	td->td_frame->tf_eflags |= PSL_T;
	return (0);
}

int
fill_regs(struct thread *td, struct reg *regs)
{
	struct pcb *pcb;
	struct trapframe *tp;

	tp = td->td_frame;
	regs->r_fs = tp->tf_fs;
	regs->r_es = tp->tf_es;
	regs->r_ds = tp->tf_ds;
	regs->r_edi = tp->tf_edi;
	regs->r_esi = tp->tf_esi;
	regs->r_ebp = tp->tf_ebp;
	regs->r_ebx = tp->tf_ebx;
	regs->r_edx = tp->tf_edx;
	regs->r_ecx = tp->tf_ecx;
	regs->r_eax = tp->tf_eax;
	regs->r_eip = tp->tf_eip;
	regs->r_cs = tp->tf_cs;
	regs->r_eflags = tp->tf_eflags;
	regs->r_esp = tp->tf_esp;
	regs->r_ss = tp->tf_ss;
	pcb = td->td_pcb;
	regs->r_gs = pcb->pcb_gs;
	return (0);
}

int
set_regs(struct thread *td, struct reg *regs)
{
	struct pcb *pcb;
	struct trapframe *tp;

	tp = td->td_frame;
	if (!EFL_SECURE(regs->r_eflags, tp->tf_eflags) ||
	    !CS_SECURE(regs->r_cs))
		return (EINVAL);
	tp->tf_fs = regs->r_fs;
	tp->tf_es = regs->r_es;
	tp->tf_ds = regs->r_ds;
	tp->tf_edi = regs->r_edi;
	tp->tf_esi = regs->r_esi;
	tp->tf_ebp = regs->r_ebp;
	tp->tf_ebx = regs->r_ebx;
	tp->tf_edx = regs->r_edx;
	tp->tf_ecx = regs->r_ecx;
	tp->tf_eax = regs->r_eax;
	tp->tf_eip = regs->r_eip;
	tp->tf_cs = regs->r_cs;
	tp->tf_eflags = regs->r_eflags;
	tp->tf_esp = regs->r_esp;
	tp->tf_ss = regs->r_ss;
	pcb = td->td_pcb;
	pcb->pcb_gs = regs->r_gs;
	return (0);
}

#ifdef CPU_ENABLE_SSE
static void
fill_fpregs_xmm(sv_xmm, sv_87)
	struct savexmm *sv_xmm;
	struct save87 *sv_87;
{
	register struct env87 *penv_87 = &sv_87->sv_env;
	register struct envxmm *penv_xmm = &sv_xmm->sv_env;
	int i;

	bzero(sv_87, sizeof(*sv_87));

	/* FPU control/status */
	penv_87->en_cw = penv_xmm->en_cw;
	penv_87->en_sw = penv_xmm->en_sw;
	penv_87->en_tw = penv_xmm->en_tw;
	penv_87->en_fip = penv_xmm->en_fip;
	penv_87->en_fcs = penv_xmm->en_fcs;
	penv_87->en_opcode = penv_xmm->en_opcode;
	penv_87->en_foo = penv_xmm->en_foo;
	penv_87->en_fos = penv_xmm->en_fos;

	/* FPU registers */
	for (i = 0; i < 8; ++i)
		sv_87->sv_ac[i] = sv_xmm->sv_fp[i].fp_acc;
}

static void
set_fpregs_xmm(sv_87, sv_xmm)
	struct save87 *sv_87;
	struct savexmm *sv_xmm;
{
	register struct env87 *penv_87 = &sv_87->sv_env;
	register struct envxmm *penv_xmm = &sv_xmm->sv_env;
	int i;

	/* FPU control/status */
	penv_xmm->en_cw = penv_87->en_cw;
	penv_xmm->en_sw = penv_87->en_sw;
	penv_xmm->en_tw = penv_87->en_tw;
	penv_xmm->en_fip = penv_87->en_fip;
	penv_xmm->en_fcs = penv_87->en_fcs;
	penv_xmm->en_opcode = penv_87->en_opcode;
	penv_xmm->en_foo = penv_87->en_foo;
	penv_xmm->en_fos = penv_87->en_fos;

	/* FPU registers */
	for (i = 0; i < 8; ++i)
		sv_xmm->sv_fp[i].fp_acc = sv_87->sv_ac[i];
}
#endif /* CPU_ENABLE_SSE */

int
fill_fpregs(struct thread *td, struct fpreg *fpregs)
{
#ifdef CPU_ENABLE_SSE
	if (cpu_fxsr) {
		fill_fpregs_xmm(&td->td_pcb->pcb_save.sv_xmm,
						(struct save87 *)fpregs);
		return (0);
	}
#endif /* CPU_ENABLE_SSE */
	bcopy(&td->td_pcb->pcb_save.sv_87, fpregs, sizeof *fpregs);
	return (0);
}

int
set_fpregs(struct thread *td, struct fpreg *fpregs)
{
#ifdef CPU_ENABLE_SSE
	if (cpu_fxsr) {
		set_fpregs_xmm((struct save87 *)fpregs,
					   &td->td_pcb->pcb_save.sv_xmm);
		return (0);
	}
#endif /* CPU_ENABLE_SSE */
	bcopy(fpregs, &td->td_pcb->pcb_save.sv_87, sizeof *fpregs);
	return (0);
}

/*
 * Get machine context.
 */
int
get_mcontext(struct thread *td, mcontext_t *mcp)
{
	struct trapframe *tp;

	tp = td->td_frame;

	mcp->mc_onstack = sigonstack(tp->tf_esp);
	mcp->mc_gs = td->td_pcb->pcb_gs;
	mcp->mc_fs = tp->tf_fs;
	mcp->mc_es = tp->tf_es;
	mcp->mc_ds = tp->tf_ds;
	mcp->mc_edi = tp->tf_edi;
	mcp->mc_esi = tp->tf_esi;
	mcp->mc_ebp = tp->tf_ebp;
	mcp->mc_isp = tp->tf_isp;
	mcp->mc_ebx = tp->tf_ebx;
	mcp->mc_edx = tp->tf_edx;
	mcp->mc_ecx = tp->tf_ecx;
	mcp->mc_eax = tp->tf_eax;
	mcp->mc_eip = tp->tf_eip;
	mcp->mc_cs = tp->tf_cs;
	mcp->mc_eflags = tp->tf_eflags;
	mcp->mc_esp = tp->tf_esp;
	mcp->mc_ss = tp->tf_ss;
	mcp->mc_len = sizeof(*mcp);
	get_fpcontext(td, mcp);
	return (0);
}

/*
 * Set machine context.
 *
 * However, we don't set any but the user modifiable flags, and we won't
 * touch the cs selector.
 */
int
set_mcontext(struct thread *td, const mcontext_t *mcp)
{
	struct trapframe *tp;
	int eflags, ret;

	tp = td->td_frame;
	if (mcp->mc_len != sizeof(*mcp))
		return (EINVAL);
	eflags = (mcp->mc_eflags & PSL_USERCHANGE) |
	    (tp->tf_eflags & ~PSL_USERCHANGE);
	if ((ret = set_fpcontext(td, mcp)) == 0) {
		tp->tf_fs = mcp->mc_fs;
		tp->tf_es = mcp->mc_es;
		tp->tf_ds = mcp->mc_ds;
		tp->tf_edi = mcp->mc_edi;
		tp->tf_esi = mcp->mc_esi;
		tp->tf_ebp = mcp->mc_ebp;
		tp->tf_ebx = mcp->mc_ebx;
		tp->tf_edx = mcp->mc_edx;
		tp->tf_ecx = mcp->mc_ecx;
		tp->tf_eax = mcp->mc_eax;
		tp->tf_eip = mcp->mc_eip;
		tp->tf_eflags = eflags;
		tp->tf_esp = mcp->mc_esp;
		tp->tf_ss = mcp->mc_ss;
		td->td_pcb->pcb_gs = mcp->mc_gs;
		ret = 0;
	}
	return (ret);
}

static void
get_fpcontext(struct thread *td, mcontext_t *mcp)
{
#ifndef DEV_NPX
	mcp->mc_fpformat = _MC_FPFMT_NODEV;
	mcp->mc_ownedfp = _MC_FPOWNED_NONE;
#else
	union savefpu *addr;

	/*
	 * XXX mc_fpstate might be misaligned, since its declaration is not
	 * unportabilized using __attribute__((aligned(16))) like the
	 * declaration of struct savemm, and anyway, alignment doesn't work
	 * for auto variables since we don't use gcc's pessimal stack
	 * alignment.  Work around this by abusing the spare fields after
	 * mcp->mc_fpstate.
	 *
	 * XXX unpessimize most cases by only aligning when fxsave might be
	 * called, although this requires knowing too much about
	 * npxgetregs()'s internals.
	 */
	addr = (union savefpu *)&mcp->mc_fpstate;
	if (td == PCPU_GET(fpcurthread) &&
#ifdef CPU_ENABLE_SSE
	    cpu_fxsr &&
#endif
	    ((uintptr_t)(void *)addr & 0xF)) {
		do
			addr = (void *)((char *)addr + 4);
		while ((uintptr_t)(void *)addr & 0xF);
	}
	mcp->mc_ownedfp = npxgetregs(td, addr);
	if (addr != (union savefpu *)&mcp->mc_fpstate) {
		bcopy(addr, &mcp->mc_fpstate, sizeof(mcp->mc_fpstate));
		bzero(&mcp->mc_spare2, sizeof(mcp->mc_spare2));
	}
	mcp->mc_fpformat = npxformat();
#endif
}

static int
set_fpcontext(struct thread *td, const mcontext_t *mcp)
{
	union savefpu *addr;

	if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
		return (0);
	else if (mcp->mc_fpformat != _MC_FPFMT_387 &&
	    mcp->mc_fpformat != _MC_FPFMT_XMM)
		return (EINVAL);
	else if (mcp->mc_ownedfp == _MC_FPOWNED_NONE)
		/* We don't care what state is left in the FPU or PCB. */
		fpstate_drop(td);
	else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
	    mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
		/* XXX align as above. */
		addr = (union savefpu *)&mcp->mc_fpstate;
		if (td == PCPU_GET(fpcurthread) &&
#ifdef CPU_ENABLE_SSE
		    cpu_fxsr &&
#endif
		    ((uintptr_t)(void *)addr & 0xF)) {
			do
				addr = (void *)((char *)addr + 4);
			while ((uintptr_t)(void *)addr & 0xF);
			bcopy(&mcp->mc_fpstate, addr, sizeof(mcp->mc_fpstate));
		}
#ifdef DEV_NPX
		/*
		 * XXX we violate the dubious requirement that npxsetregs()
		 * be called with interrupts disabled.
		 */
		npxsetregs(td, addr);
#endif
		/*
		 * Don't bother putting things back where they were in the
		 * misaligned case, since we know that the caller won't use
		 * them again.
		 */
	} else
		return (EINVAL);
	return (0);
}

static void
fpstate_drop(struct thread *td)
{
	register_t s;

	s = intr_disable();
#ifdef DEV_NPX
	if (PCPU_GET(fpcurthread) == td)
		npxdrop();
#endif
	/*
	 * XXX force a full drop of the npx.  The above only drops it if we
	 * owned it.  npxgetregs() has the same bug in the !cpu_fxsr case.
	 *
	 * XXX I don't much like npxgetregs()'s semantics of doing a full
	 * drop.  Dropping only to the pcb matches fnsave's behaviour.
	 * We only need to drop to !PCB_INITDONE in sendsig().  But
	 * sendsig() is the only caller of npxgetregs()... perhaps we just
	 * have too many layers.
	 */
	curthread->td_pcb->pcb_flags &= ~PCB_NPXINITDONE;
	intr_restore(s);
}

int
fill_dbregs(struct thread *td, struct dbreg *dbregs)
{
	struct pcb *pcb;

	if (td == NULL) {
		dbregs->dr[0] = rdr0();
		dbregs->dr[1] = rdr1();
		dbregs->dr[2] = rdr2();
		dbregs->dr[3] = rdr3();
		dbregs->dr[4] = rdr4();
		dbregs->dr[5] = rdr5();
		dbregs->dr[6] = rdr6();
		dbregs->dr[7] = rdr7();
	} else {
		pcb = td->td_pcb;
		dbregs->dr[0] = pcb->pcb_dr0;
		dbregs->dr[1] = pcb->pcb_dr1;
		dbregs->dr[2] = pcb->pcb_dr2;
		dbregs->dr[3] = pcb->pcb_dr3;
		dbregs->dr[4] = 0;
		dbregs->dr[5] = 0;
		dbregs->dr[6] = pcb->pcb_dr6;
		dbregs->dr[7] = pcb->pcb_dr7;
	}
	return (0);
}

int
set_dbregs(struct thread *td, struct dbreg *dbregs)
{
	struct pcb *pcb;
	int i;
	u_int32_t mask1, mask2;

	if (td == NULL) {
		load_dr0(dbregs->dr[0]);
		load_dr1(dbregs->dr[1]);
		load_dr2(dbregs->dr[2]);
		load_dr3(dbregs->dr[3]);
		load_dr4(dbregs->dr[4]);
		load_dr5(dbregs->dr[5]);
		load_dr6(dbregs->dr[6]);
		load_dr7(dbregs->dr[7]);
	} else {
		/*
		 * Don't let an illegal value for dr7 get set.	Specifically,
		 * check for undefined settings.  Setting these bit patterns
		 * result in undefined behaviour and can lead to an unexpected
		 * TRCTRAP.
		 */
		for (i = 0, mask1 = 0x3<<16, mask2 = 0x2<<16; i < 8;
		     i++, mask1 <<= 2, mask2 <<= 2)
			if ((dbregs->dr[7] & mask1) == mask2)
				return (EINVAL);

		pcb = td->td_pcb;

		/*
		 * Don't let a process set a breakpoint that is not within the
		 * process's address space.  If a process could do this, it
		 * could halt the system by setting a breakpoint in the kernel
		 * (if ddb was enabled).  Thus, we need to check to make sure
		 * that no breakpoints are being enabled for addresses outside
		 * process's address space, unless, perhaps, we were called by
		 * uid 0.
		 *
		 * XXX - what about when the watched area of the user's
		 * address space is written into from within the kernel
		 * ... wouldn't that still cause a breakpoint to be generated
		 * from within kernel mode?
		 */

		if (suser(td) != 0) {
			if (dbregs->dr[7] & 0x3) {
				/* dr0 is enabled */
				if (dbregs->dr[0] >= VM_MAXUSER_ADDRESS)
					return (EINVAL);
			}

			if (dbregs->dr[7] & (0x3<<2)) {
				/* dr1 is enabled */
				if (dbregs->dr[1] >= VM_MAXUSER_ADDRESS)
					return (EINVAL);
			}

			if (dbregs->dr[7] & (0x3<<4)) {
				/* dr2 is enabled */
				if (dbregs->dr[2] >= VM_MAXUSER_ADDRESS)
					return (EINVAL);
			}

			if (dbregs->dr[7] & (0x3<<6)) {
				/* dr3 is enabled */
				if (dbregs->dr[3] >= VM_MAXUSER_ADDRESS)
					return (EINVAL);
			}
		}

		pcb->pcb_dr0 = dbregs->dr[0];
		pcb->pcb_dr1 = dbregs->dr[1];
		pcb->pcb_dr2 = dbregs->dr[2];
		pcb->pcb_dr3 = dbregs->dr[3];
		pcb->pcb_dr6 = dbregs->dr[6];
		pcb->pcb_dr7 = dbregs->dr[7];

		pcb->pcb_flags |= PCB_DBREGS;
	}

	return (0);
}

/*
 * Return > 0 if a hardware breakpoint has been hit, and the
 * breakpoint was in user space.  Return 0, otherwise.
 */
int
user_dbreg_trap(void)
{
        u_int32_t dr7, dr6; /* debug registers dr6 and dr7 */
        u_int32_t bp;       /* breakpoint bits extracted from dr6 */
        int nbp;            /* number of breakpoints that triggered */
        caddr_t addr[4];    /* breakpoint addresses */
        int i;

        dr7 = rdr7();
        if ((dr7 & 0x000000ff) == 0) {
                /*
                 * all GE and LE bits in the dr7 register are zero,
                 * thus the trap couldn't have been caused by the
                 * hardware debug registers
                 */
                return 0;
        }

        nbp = 0;
        dr6 = rdr6();
        bp = dr6 & 0x0000000f;

        if (!bp) {
                /*
                 * None of the breakpoint bits are set meaning this
                 * trap was not caused by any of the debug registers
                 */
                return 0;
        }

        /*
         * at least one of the breakpoints were hit, check to see
         * which ones and if any of them are user space addresses
         */

        if (bp & 0x01) {
                addr[nbp++] = (caddr_t)rdr0();
        }
        if (bp & 0x02) {
                addr[nbp++] = (caddr_t)rdr1();
        }
        if (bp & 0x04) {
                addr[nbp++] = (caddr_t)rdr2();
        }
        if (bp & 0x08) {
                addr[nbp++] = (caddr_t)rdr3();
        }

        for (i=0; i<nbp; i++) {
                if (addr[i] <
                    (caddr_t)VM_MAXUSER_ADDRESS) {
                        /*
                         * addr[i] is in user space
                         */
                        return nbp;
                }
        }

        /*
         * None of the breakpoints are in user space.
         */
        return 0;
}


#ifndef DDB
void
Debugger(const char *msg)
{
	printf("Debugger(\"%s\") called.\n", msg);
}
#endif /* no DDB */

#ifdef DDB

/*
 * Provide inb() and outb() as functions.  They are normally only
 * available as macros calling inlined functions, thus cannot be
 * called inside DDB.
 *
 * The actual code is stolen from <machine/cpufunc.h>, and de-inlined.
 */

#undef inb
#undef outb

/* silence compiler warnings */
u_char inb(u_int);
void outb(u_int, u_char);

u_char
inb(u_int port)
{
	u_char	data;
	/*
	 * We use %%dx and not %1 here because i/o is done at %dx and not at
	 * %edx, while gcc generates inferior code (movw instead of movl)
	 * if we tell it to load (u_short) port.
	 */
	__asm __volatile("inb %%dx,%0" : "=a" (data) : "d" (port));
	return (data);
}

void
outb(u_int port, u_char data)
{
	u_char	al;
	/*
	 * Use an unnecessary assignment to help gcc's register allocator.
	 * This make a large difference for gcc-1.40 and a tiny difference
	 * for gcc-2.6.0.  For gcc-1.40, al had to be ``asm("ax")'' for
	 * best results.  gcc-2.6.0 can't handle this.
	 */
	al = data;
	__asm __volatile("outb %0,%%dx" : : "a" (al), "d" (port));
}

#endif /* DDB */