Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r249846:

When rebooting (exiting) from the BTX loader, make sure to restore the
GDT from the correct segment, otherwise a triple fault would be caused.
In some virtual environments (VMware, VirtualBox, etc) this could lead
to a unhandled error or hang in the guest emulation software.

Thanks to avg and jhb for a few hints in the right direction.

Noticed by: Jeremy Chadwick <jdc@koitsu.org> (and many others)

MFC: r239063, r239064, r239069, r240852, r240854

- boot2: bunch of variables are turned into uint8_t.
- boot2: Remove unnecessary initializations.
- loader: replace ugly inb/outb re-implementations with cpufunc.h.
- Reduce diffs against i386.

MFC: r242863

add detection of serial console presence to btx and boot2-like blocks.

MFC r235264: MFi386: improve argument passing via btxldr

MFC r232263:

Define several extra macros in bsd.sys.mk and sys/conf/kern.pre.mk, to
get rid of testing explicitly for clang (using ${CC:T:Mclang}) in
individual Makefiles.

Instead, use the following extra macros, for use with clang:
- NO_WERROR.clang (disables -Werror)
- NO_WCAST_ALIGN.clang (disables -Wcast-align)
- NO_WFORMAT.clang (disables -Wformat and friends)
- CLANG_NO_IAS (disables integrated assembler)
- CLANG_OPT_SMALL (adds flags for extra small size optimizations)

As a side effect, this enables setting CC/CXX/CPP in src.conf instead of
make.conf! For clang, use the following:

CC=clang
CXX=clang++
CPP=clang-cpp

MFC 226746:
Consolidate duplicate definitions of V86_CY() and V86_ZR() which check for
the carry and zero flags being set, respectively, in <btxv86.h> and use
them throughout the x86 boot code.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Upgrade our copy of llvm/clang to r126079, from upstream's trunk.

This contains many improvements, primarily better C++ support, an
integrated assembler for x86 and support for -pg.

Use -Wl,-N instead of the undocumented -N option for GCC.

GCC forwards the -N flag directly to ld. This flag is not documented and
not supported by (for example) Clang. Just use -Wl,-N.

Submitted by: Pawel Worach

MFi386: Use real mode instead of v86 mode.

MFC after: 1 week

MFi386:

Retire the support for using paging in BTX. It hasn't been used since
before 4.0.

MFi386: revisions from 1.39 to 1.43.

Remove ifdef PC98.

Start the dreaded NOFOO -> NO_FOO conversion.

OK'ed by: core

MFi386: revision 1.38.

MFi386: revision 1.4.

MFi386: revisions from 1.15 to 1.17.

MFi386: revisions from 1.16 to 1.18.

MFi386: Use C (and CPP) style comments for assembler-with-cpp
sources, for lines that start with a comment.

MFi386: Get rid of unnecessary use of m4(1) by using cpp(1) instead.

Repocopied by: joe

MFi386: Factor out -nostdlib and use PROG.

MFi386: Cleanups to sys/boot makefiles.

MFi386: revision 1.33

PR: kern/62005

MFi386: revision 1.13.

Switch to using bsd.prog.mk; this gives us back the standard
.s.o transformation rule.

Remove -elf option.

Initiate deorbit burn for the i386-only a.out related support. Moves are
under way to move the remnants of the a.out toolchain to ports. As the
comment in src/Makefile said, this stuff is deprecated and one should not
expect this to remain beyond 4.0-REL. It has already lasted WAY beyond
that.

Notable exceptions:
gcc - I have not touched the a.out generation stuff there.
ldd/ldconfig - still have some code to interface with a.out rtld.
old as/ld/etc - I have not removed these yet, pending their move to ports.
some includes - necessary for ldd/ldconfig for now.

Tested on: i386 (extensively), alpha

Fixed CLEANFILES after bsd.lib.mk sweep.

Major cleanup of bsd.lib.mk.

Get rid of the INTERNALSTATICLIB knob and just use plain INTERNALLIB.
INTERNALLIB now means to build static library only and don't install
anything. Added a NOINSTALLLIB knob for libpam/modules. To not
build any library at all, just do not set LIB.

Back out last commit. I expect our bsd.*.mk gods to remove the need for
defining so many extra things in addition to INTERNALLIB. We don't like
repetitive C code and we shouldn't for make code either.

NOPIC, NOPROFILE, NOMAN, and INTERNALSTATICLIB are redundant when using
INTERNALLIB now.

MFi386: revisions from 1.26 to 1.30.

MFi386: revision 1.12

Merged from sys/boot/i386/btx/btx/btx.s revision 1.25.

Merged from sys/boot/i386/btx/btx/btx.s revision 1.24.

Merged from the following changes.

sys/boot/i386/btx/btx/Makefile 1.9
sys/boot/i386/btx/btx/btx.s 1.23
sys/boot/i386/libi386/biosdisk.c 1.32 and 1.33
sys/boot/i386/libi386/biosmem.c 1.5
sys/boot/i386/libi386/comconsole.c 1.8
sys/boot/i386/libi386/gatea20.c 1.3
sys/boot/i386/libi386/time.c 1.4
sys/boot/i386/libi386/vidconsole.c 1.13
sys/boot/i386/loader/Makefile 1.48
sys/boot/i386/loader/main.c 1.22

Merged from sys/boot/i386/btx/btx/btx.s revisions from 1.18 to 1.22.

Sync with the following changes.

sys/boot/i386/btx/btx/Makefile 1.8
sys/boot/i386/btx/btx/btx.s 1.16 and 1.17
sys/boot/i386/btx/btxldr/btxldr.s 1.10
sys/boot/i386/loader/Makefile 1.45

Synced with following files:
src/sys/boot/i386/Makefile.inc 1.1
src/sys/boot/i386/btx/btx/btx.s 1.15
src/sys/boot/i386/btx/btxldr/Makefile 1.8
src/sys/boot/i386/btx/btxldr/btxldr.s 1.9
src/sys/boot/i386/libi386/biosdisk.c 1.29
src/sys/boot/i386/loader/Makefile 1.42
src/sys/boot/i386/loader/main.c 1.18
(entry point address of loader was not changed.)

Reviewed by: nyan

Synced with sys/boot/i386/btx/btx/btx.s rev 1.14.

Sync with sys/boot/i386/btx/btx/btx.s revision 1.13.

Sync with sys/boot/i386/btx/btx/Makefile and btx.s revisions 1.7 and
1.12, respectively.

Blank out the twiddly thing when outputting the ``BTX loader'' message.

$Id$ -> $FreeBSD$

Sync with sys/boot/i386/btx/Makefile revision 1.5.

Sync with sys/boot/i386/btx/btx/btx.s revision 1.10.

PC98 version of new boot loader. Because boot2 has not yet ported,
files in boot2 directory are copies from legacy biosboot.

Submitted by: IMAI Takeshi <take-i@ceres.dti.ne.jp>