Back out the following revisions on behalf of core:

sys/sys/lwp.h: revision 1.228
sys/sys/pipe.h: revision 1.40
sys/kern/uipc_socket.c: revision 1.306
sys/kern/kern_sleepq.c: revision 1.84
sys/rump/librump/rumpkern/locks_up.c: revision 1.13
sys/kern/sys_pipe.c: revision 1.165
usr.bin/fstat/fstat.c: revision 1.119
sys/rump/librump/rumpkern/locks.c: revision 1.87
sys/ddb/db_xxx.c: revision 1.78
sys/ddb/db_command.c: revision 1.187
sys/sys/condvar.h: revision 1.18
sys/ddb/db_interface.h: revision 1.42
sys/sys/socketvar.h: revision 1.166
sys/kern/uipc_syscalls.c: revision 1.209
sys/kern/kern_condvar.c: revision 1.60

Add cv_fdrestart() [...]
Use cv_fdrestart() to implement fo_restart.
Simplify/streamline pipes a little bit [...]

This changes have caused regressions and need to be debugged.
The cv_fdrestart() addition needs more discussion.

When converting from db_expr_t to a pointer cast via uintptr_t
to help kernels where the size differs (e.g. 32bit sparc64 kernels)

Simplify/streamline pipes a little bit:

- Allocate only one struct pipe not two (no need to be bidirectional here).
- Then use f_flag (FREAD/FWRITE) to figure out what to do in the fileops.
- Never wake the other side or acquire long-term (I/O) lock unless needed.
- Whenever possible, defer wakeups until after locks have been released.
- Do some things locklessly in pipe_ioctl() and pipe_poll().

Some notable results:

- -30% latency on a 486DX2/66 doing 1 byte ping-pong within a single process.
- 2.5x less lock contention during "make cleandir" of src on a 48 CPU machine.
- 1.5x bandwith with 1kB messages on the same 48 CPU machine (8kB: same b/w).

For architectures (mips64) where sizeof(db_expr_t) != sizeof(kcondvar_t *)
cast through uintptr_t.

Add some simple DDB show commands: condvar, selinfo, sleepq

Move proc_lock into the data segment. It was dynamically allocated because
at the time we had mutex_obj_alloc() but not __cacheline_aligned.

Make the db_kernelonly() macro visible to all files and re-use it.
Register access is kernel only.

Load struct fdfile::ff_file with atomic_load_consume.

Exceptions: when we're only testing whether it's there, not about to
dereference it.

Note: We do not use atomic_store_release to set it because the
preceding mutex_exit should be enough.

(That said, it's not clear the mutex_enter/exit is needed unless
refcnt > 0 already, in which case maybe it would be a win to switch
from the membar implied by mutex_enter to the membar implied by
atomic_store_release -- which I would generally expect to be much
cheaper. And a little clearer without a long comment.)

Load struct filedesc::fd_dt with atomic_load_consume.

Exceptions: when fd_refcnt <= 1, or when holding fd_lock.

While here:

- Restore KASSERT(mutex_owned(&fdp->fd_lock)) in fd_unused.
=> This is used only in fd_close and fd_abort, where it holds.
- Move bounds check assertion in fd_putfile to where it matters.
- Store fd_dt with atomic_store_release.
- Move load of fd_dt under lock in knote_fdclose.
- Omit membar_consumer in fdesc_readdir.
=> atomic_load_consume serves the same purpose now.
=> Was needed only on alpha anyway.

branches: 1.71.18; 1.71.24;
Don't use an unset value as an address

Instead, show usage if no address is passed.

branches: 1.70.2;
Try not to use f_data, use f_{vnode,socket,pipe,mqueue,kqueue,ksem} to get
a correctly typed pointer.

remove previous, dmesg just works.

Add "show dmesg" that prints the contents of the message buffer.

Add "show panic" that shows the current panic string. two ports had it, and
it could be easily made MI.

branches: 1.66.8;
If we are DIAGNOSTIC don't try to go further if we failed to take the
lock, because we are going to trigger a KASSERT. Also hold the lock
longer and take the proc lock for kpsignal(). Maybe we should add
mutex_steal() and mutex_return() for the debugger? Lock correction
suggestion from jmcneill.

deal with the proc_lock mutex.

branches: 1.64.2;
Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.

branches: 1.63.2;
re-instate db_kill_proc

branches: 1.62.4; 1.62.6;
Add #ifdef MQUEUE for db_show_mqueue_cmd().

XXX: Wrong. DDB should be dynamic, modular, etc.

More changes to improve kern_descrip.c.

- Avoid atomics in more places.
- Remove the per-descriptor mutex, and just use filedesc_t::fd_lock.
It was only being used to synchronize close, and in any case we needed
to take fd_lock to free the descriptor slot.
- Optimize certain paths for the <NDFDFILE case.
- Sprinkle more comments and assertions.
- Cache more stuff in filedesc_t.
- Fix numerous minor bugs spotted along the way.
- Restructure how the open files array is maintained, for clarity and so
that we can eliminate the membar_consumer() call in fd_getfile(). This is
mostly syntactic sugar; the main functional change is that fd_nfiles now
lives alongside the open file array.

Some measurements with libmicro:

- simple file syscalls are like close() are between 1 to 10% faster.
- some nice improvements, e.g. poll(1000) which is ~50% faster.

Make 'show event', 'dmesg' work with crash(8).
XXX dmesg fails exactly the same way as /sbin/dmesg.

include <stdbool.h> if not _KERNEL, and don't include kauth.h if _KERNEL.

now crash builds on i386.

include ddb headers *after* sys/types.h or sys/param.h.

Make ddb compile and work in userspace. Mostly this is comprised of three
types of changes:

- Add a few new methods to replace stuff like p_find(), CPU_INFO_FOREACH.

- Use db_read_bytes() instead of accessing kernel structures directly,
and similar changes.

- Add ifdef _KERNEL where the above hasn't been done, and an XXX comment.

- fix vmem unittest. rename VMEM_DEBUG so that it won't be abused again.
- reimplement vmem sanity checks with less code duplication.
- reimplement ddb vmem-related commands in a more consistent ways.
remove automatic whatis.

branches: 1.55.2;
Default 'show all procs' to /l. People tend to type 'ps' without modifiers
when providing information about deadlocks. Without the thread info it's
not very useful.

Add some basic DDB stuff for modules.

ifdef AIO

branches: 1.52.2; 1.52.4;
Replace more intptr_t to uintptr_t when casting VA.

Take care not to dereference NULL datapointer from fd table
Make output more readable and label what lock we are examining.

Fix indents.

Add a show files command that prints the vnodes associated with a
given struct proc and, if LOCKDEBUG is built in, the lock status of
the uvmobject.

branches: 1.48.14; 1.48.18; 1.48.20; 1.48.22; 1.48.24;
ps/w: display LWP info.

branches: 1.47.6;
Implementation of POSIX message queues.

Reviewed by: <ad>, <tech-kern>

branches: 1.46.4; 1.46.6; 1.46.8;
include cdefs.h before opt_xxx.h

branches: 1.45.2;
Merge some of the less invasive changes from the vmlocking branch:

- kthread, callout, devsw API changes
- select()/poll() improvements
- miscellaneous MT safety improvements

merge yamt-idlelwp branch. asked by core@. some ports still needs work.

from doc/BRANCHES:

idle lwp, and some changes depending on it.

1. separate context switching and thread scheduling.
(cf. gmcgarry_ctxsw)
2. implement idle lwp.
3. clean up related MD/MI interfaces.
4. make scheduler(s) modular.

Import of POSIX Asynchronous I/O.
Seems to be quite stable. Some work still left to do.

Please note, that syscalls are not yet MP-safe, because
of the file and vnode subsystems.

Reviewed by: <tech-kern>, <ad>

branches: 1.42.4; 1.42.6;
Fix lossage from boolean_t -> bool and updated x86 bus_dma.

branches: 1.41.2;
Merge newlock2 to head.

__unused removal on arguments; approved by core.

- sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386

branches: 1.38.8; 1.38.10;
integrate kauth.

branches: 1.37.2; 1.37.4; 1.37.6; 1.37.8; 1.37.10;
db_show_sched_qs: fix pointer cast lint considers troublesome.

Add /l to show all procs usage.

This is not IOCCC. Replace " >"[cp == p] with conditional expression.
Makes lint happy. Probably generates better code too (does on sh3).

branches: 1.34.2;
After addition of "show all pools", we now need <sys/pool.h> here.
Fixes build problem for mac68k.

add "show all pools" command for ddb.

- change the way to specify a bufq strategy. (by string rather than by number)
- rather than embedding bufq_state in driver softc,
have a pointer to the former.
- move bufq related functions from kern/subr_disk.c to kern/subr_bufq.c.
- rename method to strategy for consistency.
- move some definitions which don't need to be exposed to the rest of kernel
from sys/bufq.h to sys/bufq_impl.h.
(is it better to move it to kern/ or somewhere?)
- fix some obvious breakage in dev/qbus/ts.c. (not tested)

branches: 1.31.2;
more constification fallout

nuke trailing whitespace

branches: 1.29.4; 1.29.6;
Make ddb's "show sched_qs" aware of big-endian sched_qs arrangements.

Add a "show sched_qs" command to dump the run queues. Format is:
1 pid.lid (p_comm)
pid.lid (p_comm)
...

If a queue has procs, but no sched_whichqs bit, it shows:
!1 pid.lid (p_comm)

Widen FLAGS column for ps/l so that all defined l_flag flags fit.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.25.2;
Allow the dmesg command to show the last N bytes of the kernel message
buffer.

Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

(1) Don't print the message buffer (via ddb's dmesg command) if the
message buffer has not yet been set up, mimicking code from the top of
the sysctl routine for retrieving the message buffer.

(2) Add a /l modifier to the trace command. This makes it print the
backtrace using printf() instead of db_printf(), which has the nice
side-effect of also putting it into the message buffer. A kernel with
ddb in it but disabled (ie, ddb.onpanic set to zero) will print a
backtrace (which ends up in the message buffer) before dumping (or
not, depending on the value of kern.dump_on_panic) and rebooting, but
if ddb is not disabled, the backtrace is not printed, and there's no
way to get it to display a backtrace such that you can retrieve it
after the dump. The backtrace printed by gdb is sometimes a little
different.

(3) Documentation for the above.

Add a rudimentary 'trap to kgdb' command if KGDB is defined. This allows
systems with only one serial port for console, etc., to have at least some
basic access to remote-kgdb-over-serial, even if it is a bit awkward.

New callout implementation. This is based on callwheel implementation
done by Artur Grabowski and Thomas Nordin for OpenBSD, which is more
efficient in several ways than the callwheel implementation that it is
replacing. It has been adapted to our pre-existing callout API, and
also provides the slightly more efficient (and much more intuitive)
API (adapted to the callout_*() naming scheme) that the OpenBSD version
provides.

Among other things, this shaves a bunch of cycles off rescheduling-in-
the-future a callout which is already scheduled, which the common case
for TCP timers (notably REXMT and KEEP).

The API has been simplified a bit, as well. The (very confusing to
a good many people) "ACTIVE" state for callouts has gone away. There
is now only "PENDING" (scheduled to fire in the future) and "EXPIRED"
(has fired, and the function called).

Kernel version bump not done; we'll ride the 1.6N bump that happened
with the malloc(9) change.

Zombie procs have no lwps.

Merge the nathanw_sa branch.

branches: 1.17.2;
Casting from a pointer, to a db_expr_t, has to go via an intptr_t.
(db_expr_t == int64_t on sh5, for example).

branches: 1.16.8;
ANSIfy, KNF.
Make some variables and functions static when not used outside of a module.
Make variables in headers extern.
Delete the unused db_find_watchpoint() function.

add RCSIDs

use a for loop instead of goto.

Optimization suggested by Bill Sommerfeld: Keep a hint as to the
"earliest" firing callout in a bucket. This allows us to skip
the scan up the bucket if no callouts are due in the bucket.

A cheap O(1) hint update is done at callout insertion (if new callout
is earlier than hint) and removal (is bucket empty). A thorough
refresh of the hint is done when the bucket is traversed.

This doesn't matter much on machines with small values of hz
(e.g. i386), but on systems with large values of hz (e.g. Alpha),
it has a definite positive effect.

Also, keep the callwheel stats in evcnts, so that you can view them
with "vmstat -e".

branches: 1.12.2;
Add an easy way to dump the message buffer from ddb.

branches: 1.11.2; 1.11.4;
Make sure values for a %llx are long long.

Implement db_show_callout() again.

Interface change: db_printsym() takes a third argument, pr, a function
pointer indicating how to print the symbol. This allows db_printsym()
to called in places where db_printf() is not an appropriate output
function.

While straightforward, apologies in advance if I've introduced any minor
syntax errors; I was unable to test compilation this on all the affected
platforms.

Cast timeval members to types we know the printf conversions of.

New callout mechanism with two major improvements over the old
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.

The old timeout()/untimeout() API has been removed from the kernel.

branches: 1.6.2;
XXX LOCKING XXX of allproc; DDB runs with interrupts blocked, and MD
code should suspend other processors, so this probably isn't a problem,
but the comment is added anyhow.

branches: 1.5.8;
- Use proclists[], rather than checking allproc and zombproc explicitly.
- Add some comments about locking.

Merge paddr_t changes into the main branch.

branches: 1.3.2;
Print more info on ps/w, note the current proc, and properly declare db_maxoff.

fix printf formatting of "ps" (aka "show all proc") so that lines never
overflow (always hated that).

replaced "/m" flag with:
/a == show process address info
/n == show normal process info [currently the default]
/w == show process wait/emul info

Move some DDB stuff here from kern_clock.c and kern_proc.c

When converting from db_expr_t to a pointer cast via uintptr_t
to help kernels where the size differs (e.g. 32bit sparc64 kernels)

Simplify/streamline pipes a little bit:

- Allocate only one struct pipe not two (no need to be bidirectional here).
- Then use f_flag (FREAD/FWRITE) to figure out what to do in the fileops.
- Never wake the other side or acquire long-term (I/O) lock unless needed.
- Whenever possible, defer wakeups until after locks have been released.
- Do some things locklessly in pipe_ioctl() and pipe_poll().

Some notable results:

- -30% latency on a 486DX2/66 doing 1 byte ping-pong within a single process.
- 2.5x less lock contention during "make cleandir" of src on a 48 CPU machine.
- 1.5x bandwith with 1kB messages on the same 48 CPU machine (8kB: same b/w).

For architectures (mips64) where sizeof(db_expr_t) != sizeof(kcondvar_t *)
cast through uintptr_t.

Add some simple DDB show commands: condvar, selinfo, sleepq

Move proc_lock into the data segment. It was dynamically allocated because
at the time we had mutex_obj_alloc() but not __cacheline_aligned.

Make the db_kernelonly() macro visible to all files and re-use it.
Register access is kernel only.

Load struct fdfile::ff_file with atomic_load_consume.

Exceptions: when we're only testing whether it's there, not about to
dereference it.

Note: We do not use atomic_store_release to set it because the
preceding mutex_exit should be enough.

(That said, it's not clear the mutex_enter/exit is needed unless
refcnt > 0 already, in which case maybe it would be a win to switch
from the membar implied by mutex_enter to the membar implied by
atomic_store_release -- which I would generally expect to be much
cheaper. And a little clearer without a long comment.)

Load struct filedesc::fd_dt with atomic_load_consume.

Exceptions: when fd_refcnt <= 1, or when holding fd_lock.

While here:

- Restore KASSERT(mutex_owned(&fdp->fd_lock)) in fd_unused.
=> This is used only in fd_close and fd_abort, where it holds.
- Move bounds check assertion in fd_putfile to where it matters.
- Store fd_dt with atomic_store_release.
- Move load of fd_dt under lock in knote_fdclose.
- Omit membar_consumer in fdesc_readdir.
=> atomic_load_consume serves the same purpose now.
=> Was needed only on alpha anyway.

branches: 1.71.18; 1.71.24;
Don't use an unset value as an address

Instead, show usage if no address is passed.

branches: 1.70.2;
Try not to use f_data, use f_{vnode,socket,pipe,mqueue,kqueue,ksem} to get
a correctly typed pointer.

remove previous, dmesg just works.

Add "show dmesg" that prints the contents of the message buffer.

Add "show panic" that shows the current panic string. two ports had it, and
it could be easily made MI.

branches: 1.66.8;
If we are DIAGNOSTIC don't try to go further if we failed to take the
lock, because we are going to trigger a KASSERT. Also hold the lock
longer and take the proc lock for kpsignal(). Maybe we should add
mutex_steal() and mutex_return() for the debugger? Lock correction
suggestion from jmcneill.

deal with the proc_lock mutex.

branches: 1.64.2;
Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.

branches: 1.63.2;
re-instate db_kill_proc

branches: 1.62.4; 1.62.6;
Add #ifdef MQUEUE for db_show_mqueue_cmd().

XXX: Wrong. DDB should be dynamic, modular, etc.

More changes to improve kern_descrip.c.

- Avoid atomics in more places.
- Remove the per-descriptor mutex, and just use filedesc_t::fd_lock.
It was only being used to synchronize close, and in any case we needed
to take fd_lock to free the descriptor slot.
- Optimize certain paths for the <NDFDFILE case.
- Sprinkle more comments and assertions.
- Cache more stuff in filedesc_t.
- Fix numerous minor bugs spotted along the way.
- Restructure how the open files array is maintained, for clarity and so
that we can eliminate the membar_consumer() call in fd_getfile(). This is
mostly syntactic sugar; the main functional change is that fd_nfiles now
lives alongside the open file array.

Some measurements with libmicro:

- simple file syscalls are like close() are between 1 to 10% faster.
- some nice improvements, e.g. poll(1000) which is ~50% faster.

Make 'show event', 'dmesg' work with crash(8).
XXX dmesg fails exactly the same way as /sbin/dmesg.

include <stdbool.h> if not _KERNEL, and don't include kauth.h if _KERNEL.

now crash builds on i386.

include ddb headers *after* sys/types.h or sys/param.h.

Make ddb compile and work in userspace. Mostly this is comprised of three
types of changes:

- Add a few new methods to replace stuff like p_find(), CPU_INFO_FOREACH.

- Use db_read_bytes() instead of accessing kernel structures directly,
and similar changes.

- Add ifdef _KERNEL where the above hasn't been done, and an XXX comment.

- fix vmem unittest. rename VMEM_DEBUG so that it won't be abused again.
- reimplement vmem sanity checks with less code duplication.
- reimplement ddb vmem-related commands in a more consistent ways.
remove automatic whatis.

branches: 1.55.2;
Default 'show all procs' to /l. People tend to type 'ps' without modifiers
when providing information about deadlocks. Without the thread info it's
not very useful.

Add some basic DDB stuff for modules.

ifdef AIO

branches: 1.52.2; 1.52.4;
Replace more intptr_t to uintptr_t when casting VA.

Take care not to dereference NULL datapointer from fd table
Make output more readable and label what lock we are examining.

Fix indents.

Add a show files command that prints the vnodes associated with a
given struct proc and, if LOCKDEBUG is built in, the lock status of
the uvmobject.

branches: 1.48.14; 1.48.18; 1.48.20; 1.48.22; 1.48.24;
ps/w: display LWP info.

branches: 1.47.6;
Implementation of POSIX message queues.

Reviewed by: <ad>, <tech-kern>

branches: 1.46.4; 1.46.6; 1.46.8;
include cdefs.h before opt_xxx.h

branches: 1.45.2;
Merge some of the less invasive changes from the vmlocking branch:

- kthread, callout, devsw API changes
- select()/poll() improvements
- miscellaneous MT safety improvements

merge yamt-idlelwp branch. asked by core@. some ports still needs work.

from doc/BRANCHES:

idle lwp, and some changes depending on it.

1. separate context switching and thread scheduling.
(cf. gmcgarry_ctxsw)
2. implement idle lwp.
3. clean up related MD/MI interfaces.
4. make scheduler(s) modular.

Import of POSIX Asynchronous I/O.
Seems to be quite stable. Some work still left to do.

Please note, that syscalls are not yet MP-safe, because
of the file and vnode subsystems.

Reviewed by: <tech-kern>, <ad>

branches: 1.42.4; 1.42.6;
Fix lossage from boolean_t -> bool and updated x86 bus_dma.

branches: 1.41.2;
Merge newlock2 to head.

__unused removal on arguments; approved by core.

- sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386

branches: 1.38.8; 1.38.10;
integrate kauth.

branches: 1.37.2; 1.37.4; 1.37.6; 1.37.8; 1.37.10;
db_show_sched_qs: fix pointer cast lint considers troublesome.

Add /l to show all procs usage.

This is not IOCCC. Replace " >"[cp == p] with conditional expression.
Makes lint happy. Probably generates better code too (does on sh3).

branches: 1.34.2;
After addition of "show all pools", we now need <sys/pool.h> here.
Fixes build problem for mac68k.

add "show all pools" command for ddb.

- change the way to specify a bufq strategy. (by string rather than by number)
- rather than embedding bufq_state in driver softc,
have a pointer to the former.
- move bufq related functions from kern/subr_disk.c to kern/subr_bufq.c.
- rename method to strategy for consistency.
- move some definitions which don't need to be exposed to the rest of kernel
from sys/bufq.h to sys/bufq_impl.h.
(is it better to move it to kern/ or somewhere?)
- fix some obvious breakage in dev/qbus/ts.c. (not tested)

branches: 1.31.2;
more constification fallout

nuke trailing whitespace

branches: 1.29.4; 1.29.6;
Make ddb's "show sched_qs" aware of big-endian sched_qs arrangements.

Add a "show sched_qs" command to dump the run queues. Format is:
1 pid.lid (p_comm)
pid.lid (p_comm)
...

If a queue has procs, but no sched_whichqs bit, it shows:
!1 pid.lid (p_comm)

Widen FLAGS column for ps/l so that all defined l_flag flags fit.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.25.2;
Allow the dmesg command to show the last N bytes of the kernel message
buffer.

Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

(1) Don't print the message buffer (via ddb's dmesg command) if the
message buffer has not yet been set up, mimicking code from the top of
the sysctl routine for retrieving the message buffer.

(2) Add a /l modifier to the trace command. This makes it print the
backtrace using printf() instead of db_printf(), which has the nice
side-effect of also putting it into the message buffer. A kernel with
ddb in it but disabled (ie, ddb.onpanic set to zero) will print a
backtrace (which ends up in the message buffer) before dumping (or
not, depending on the value of kern.dump_on_panic) and rebooting, but
if ddb is not disabled, the backtrace is not printed, and there's no
way to get it to display a backtrace such that you can retrieve it
after the dump. The backtrace printed by gdb is sometimes a little
different.

(3) Documentation for the above.

Add a rudimentary 'trap to kgdb' command if KGDB is defined. This allows
systems with only one serial port for console, etc., to have at least some
basic access to remote-kgdb-over-serial, even if it is a bit awkward.

New callout implementation. This is based on callwheel implementation
done by Artur Grabowski and Thomas Nordin for OpenBSD, which is more
efficient in several ways than the callwheel implementation that it is
replacing. It has been adapted to our pre-existing callout API, and
also provides the slightly more efficient (and much more intuitive)
API (adapted to the callout_*() naming scheme) that the OpenBSD version
provides.

Among other things, this shaves a bunch of cycles off rescheduling-in-
the-future a callout which is already scheduled, which the common case
for TCP timers (notably REXMT and KEEP).

The API has been simplified a bit, as well. The (very confusing to
a good many people) "ACTIVE" state for callouts has gone away. There
is now only "PENDING" (scheduled to fire in the future) and "EXPIRED"
(has fired, and the function called).

Kernel version bump not done; we'll ride the 1.6N bump that happened
with the malloc(9) change.

Zombie procs have no lwps.

Merge the nathanw_sa branch.

branches: 1.17.2;
Casting from a pointer, to a db_expr_t, has to go via an intptr_t.
(db_expr_t == int64_t on sh5, for example).

branches: 1.16.8;
ANSIfy, KNF.
Make some variables and functions static when not used outside of a module.
Make variables in headers extern.
Delete the unused db_find_watchpoint() function.

add RCSIDs

use a for loop instead of goto.

Optimization suggested by Bill Sommerfeld: Keep a hint as to the
"earliest" firing callout in a bucket. This allows us to skip
the scan up the bucket if no callouts are due in the bucket.

A cheap O(1) hint update is done at callout insertion (if new callout
is earlier than hint) and removal (is bucket empty). A thorough
refresh of the hint is done when the bucket is traversed.

This doesn't matter much on machines with small values of hz
(e.g. i386), but on systems with large values of hz (e.g. Alpha),
it has a definite positive effect.

Also, keep the callwheel stats in evcnts, so that you can view them
with "vmstat -e".

branches: 1.12.2;
Add an easy way to dump the message buffer from ddb.

branches: 1.11.2; 1.11.4;
Make sure values for a %llx are long long.

Implement db_show_callout() again.

Interface change: db_printsym() takes a third argument, pr, a function
pointer indicating how to print the symbol. This allows db_printsym()
to called in places where db_printf() is not an appropriate output
function.

While straightforward, apologies in advance if I've introduced any minor
syntax errors; I was unable to test compilation this on all the affected
platforms.

Cast timeval members to types we know the printf conversions of.

New callout mechanism with two major improvements over the old
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.

The old timeout()/untimeout() API has been removed from the kernel.

branches: 1.6.2;
XXX LOCKING XXX of allproc; DDB runs with interrupts blocked, and MD
code should suspend other processors, so this probably isn't a problem,
but the comment is added anyhow.

branches: 1.5.8;
- Use proclists[], rather than checking allproc and zombproc explicitly.
- Add some comments about locking.

Merge paddr_t changes into the main branch.

branches: 1.3.2;
Print more info on ps/w, note the current proc, and properly declare db_maxoff.

fix printf formatting of "ps" (aka "show all proc") so that lines never
overflow (always hated that).

replaced "/m" flag with:
/a == show process address info
/n == show normal process info [currently the default]
/w == show process wait/emul info

Move some DDB stuff here from kern_clock.c and kern_proc.c

Simplify/streamline pipes a little bit:

- Allocate only one struct pipe not two (no need to be bidirectional here).
- Then use f_flag (FREAD/FWRITE) to figure out what to do in the fileops.
- Never wake the other side or acquire long-term (I/O) lock unless needed.
- Whenever possible, defer wakeups until after locks have been released.
- Do some things locklessly in pipe_ioctl() and pipe_poll().

Some notable results:

- -30% latency on a 486DX2/66 doing 1 byte ping-pong within a single process.
- 2.5x less lock contention during "make cleandir" of src on a 48 CPU machine.
- 1.5x bandwith with 1kB messages on the same 48 CPU machine (8kB: same b/w).

For architectures (mips64) where sizeof(db_expr_t) != sizeof(kcondvar_t *)
cast through uintptr_t.

Add some simple DDB show commands: condvar, selinfo, sleepq

Move proc_lock into the data segment. It was dynamically allocated because
at the time we had mutex_obj_alloc() but not __cacheline_aligned.

Make the db_kernelonly() macro visible to all files and re-use it.
Register access is kernel only.

Load struct fdfile::ff_file with atomic_load_consume.

Exceptions: when we're only testing whether it's there, not about to
dereference it.

Note: We do not use atomic_store_release to set it because the
preceding mutex_exit should be enough.

(That said, it's not clear the mutex_enter/exit is needed unless
refcnt > 0 already, in which case maybe it would be a win to switch
from the membar implied by mutex_enter to the membar implied by
atomic_store_release -- which I would generally expect to be much
cheaper. And a little clearer without a long comment.)

Load struct filedesc::fd_dt with atomic_load_consume.

Exceptions: when fd_refcnt <= 1, or when holding fd_lock.

While here:

- Restore KASSERT(mutex_owned(&fdp->fd_lock)) in fd_unused.
=> This is used only in fd_close and fd_abort, where it holds.
- Move bounds check assertion in fd_putfile to where it matters.
- Store fd_dt with atomic_store_release.
- Move load of fd_dt under lock in knote_fdclose.
- Omit membar_consumer in fdesc_readdir.
=> atomic_load_consume serves the same purpose now.
=> Was needed only on alpha anyway.

branches: 1.71.18; 1.71.24;
Don't use an unset value as an address

Instead, show usage if no address is passed.

branches: 1.70.2;
Try not to use f_data, use f_{vnode,socket,pipe,mqueue,kqueue,ksem} to get
a correctly typed pointer.

remove previous, dmesg just works.

Add "show dmesg" that prints the contents of the message buffer.

Add "show panic" that shows the current panic string. two ports had it, and
it could be easily made MI.

branches: 1.66.8;
If we are DIAGNOSTIC don't try to go further if we failed to take the
lock, because we are going to trigger a KASSERT. Also hold the lock
longer and take the proc lock for kpsignal(). Maybe we should add
mutex_steal() and mutex_return() for the debugger? Lock correction
suggestion from jmcneill.

deal with the proc_lock mutex.

branches: 1.64.2;
Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.

branches: 1.63.2;
re-instate db_kill_proc

branches: 1.62.4; 1.62.6;
Add #ifdef MQUEUE for db_show_mqueue_cmd().

XXX: Wrong. DDB should be dynamic, modular, etc.

More changes to improve kern_descrip.c.

- Avoid atomics in more places.
- Remove the per-descriptor mutex, and just use filedesc_t::fd_lock.
It was only being used to synchronize close, and in any case we needed
to take fd_lock to free the descriptor slot.
- Optimize certain paths for the <NDFDFILE case.
- Sprinkle more comments and assertions.
- Cache more stuff in filedesc_t.
- Fix numerous minor bugs spotted along the way.
- Restructure how the open files array is maintained, for clarity and so
that we can eliminate the membar_consumer() call in fd_getfile(). This is
mostly syntactic sugar; the main functional change is that fd_nfiles now
lives alongside the open file array.

Some measurements with libmicro:

- simple file syscalls are like close() are between 1 to 10% faster.
- some nice improvements, e.g. poll(1000) which is ~50% faster.

Make 'show event', 'dmesg' work with crash(8).
XXX dmesg fails exactly the same way as /sbin/dmesg.

include <stdbool.h> if not _KERNEL, and don't include kauth.h if _KERNEL.

now crash builds on i386.

include ddb headers *after* sys/types.h or sys/param.h.

Make ddb compile and work in userspace. Mostly this is comprised of three
types of changes:

- Add a few new methods to replace stuff like p_find(), CPU_INFO_FOREACH.

- Use db_read_bytes() instead of accessing kernel structures directly,
and similar changes.

- Add ifdef _KERNEL where the above hasn't been done, and an XXX comment.

- fix vmem unittest. rename VMEM_DEBUG so that it won't be abused again.
- reimplement vmem sanity checks with less code duplication.
- reimplement ddb vmem-related commands in a more consistent ways.
remove automatic whatis.

branches: 1.55.2;
Default 'show all procs' to /l. People tend to type 'ps' without modifiers
when providing information about deadlocks. Without the thread info it's
not very useful.

Add some basic DDB stuff for modules.

ifdef AIO

branches: 1.52.2; 1.52.4;
Replace more intptr_t to uintptr_t when casting VA.

Take care not to dereference NULL datapointer from fd table
Make output more readable and label what lock we are examining.

Fix indents.

Add a show files command that prints the vnodes associated with a
given struct proc and, if LOCKDEBUG is built in, the lock status of
the uvmobject.

branches: 1.48.14; 1.48.18; 1.48.20; 1.48.22; 1.48.24;
ps/w: display LWP info.

branches: 1.47.6;
Implementation of POSIX message queues.

Reviewed by: <ad>, <tech-kern>

branches: 1.46.4; 1.46.6; 1.46.8;
include cdefs.h before opt_xxx.h

branches: 1.45.2;
Merge some of the less invasive changes from the vmlocking branch:

- kthread, callout, devsw API changes
- select()/poll() improvements
- miscellaneous MT safety improvements

merge yamt-idlelwp branch. asked by core@. some ports still needs work.

from doc/BRANCHES:

idle lwp, and some changes depending on it.

1. separate context switching and thread scheduling.
(cf. gmcgarry_ctxsw)
2. implement idle lwp.
3. clean up related MD/MI interfaces.
4. make scheduler(s) modular.

Import of POSIX Asynchronous I/O.
Seems to be quite stable. Some work still left to do.

Please note, that syscalls are not yet MP-safe, because
of the file and vnode subsystems.

Reviewed by: <tech-kern>, <ad>

branches: 1.42.4; 1.42.6;
Fix lossage from boolean_t -> bool and updated x86 bus_dma.

branches: 1.41.2;
Merge newlock2 to head.

__unused removal on arguments; approved by core.

- sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386

branches: 1.38.8; 1.38.10;
integrate kauth.

branches: 1.37.2; 1.37.4; 1.37.6; 1.37.8; 1.37.10;
db_show_sched_qs: fix pointer cast lint considers troublesome.

Add /l to show all procs usage.

This is not IOCCC. Replace " >"[cp == p] with conditional expression.
Makes lint happy. Probably generates better code too (does on sh3).

branches: 1.34.2;
After addition of "show all pools", we now need <sys/pool.h> here.
Fixes build problem for mac68k.

add "show all pools" command for ddb.

- change the way to specify a bufq strategy. (by string rather than by number)
- rather than embedding bufq_state in driver softc,
have a pointer to the former.
- move bufq related functions from kern/subr_disk.c to kern/subr_bufq.c.
- rename method to strategy for consistency.
- move some definitions which don't need to be exposed to the rest of kernel
from sys/bufq.h to sys/bufq_impl.h.
(is it better to move it to kern/ or somewhere?)
- fix some obvious breakage in dev/qbus/ts.c. (not tested)

branches: 1.31.2;
more constification fallout

nuke trailing whitespace

branches: 1.29.4; 1.29.6;
Make ddb's "show sched_qs" aware of big-endian sched_qs arrangements.

Add a "show sched_qs" command to dump the run queues. Format is:
1 pid.lid (p_comm)
pid.lid (p_comm)
...

If a queue has procs, but no sched_whichqs bit, it shows:
!1 pid.lid (p_comm)

Widen FLAGS column for ps/l so that all defined l_flag flags fit.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.25.2;
Allow the dmesg command to show the last N bytes of the kernel message
buffer.

Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

(1) Don't print the message buffer (via ddb's dmesg command) if the
message buffer has not yet been set up, mimicking code from the top of
the sysctl routine for retrieving the message buffer.

(2) Add a /l modifier to the trace command. This makes it print the
backtrace using printf() instead of db_printf(), which has the nice
side-effect of also putting it into the message buffer. A kernel with
ddb in it but disabled (ie, ddb.onpanic set to zero) will print a
backtrace (which ends up in the message buffer) before dumping (or
not, depending on the value of kern.dump_on_panic) and rebooting, but
if ddb is not disabled, the backtrace is not printed, and there's no
way to get it to display a backtrace such that you can retrieve it
after the dump. The backtrace printed by gdb is sometimes a little
different.

(3) Documentation for the above.

Add a rudimentary 'trap to kgdb' command if KGDB is defined. This allows
systems with only one serial port for console, etc., to have at least some
basic access to remote-kgdb-over-serial, even if it is a bit awkward.

New callout implementation. This is based on callwheel implementation
done by Artur Grabowski and Thomas Nordin for OpenBSD, which is more
efficient in several ways than the callwheel implementation that it is
replacing. It has been adapted to our pre-existing callout API, and
also provides the slightly more efficient (and much more intuitive)
API (adapted to the callout_*() naming scheme) that the OpenBSD version
provides.

Among other things, this shaves a bunch of cycles off rescheduling-in-
the-future a callout which is already scheduled, which the common case
for TCP timers (notably REXMT and KEEP).

The API has been simplified a bit, as well. The (very confusing to
a good many people) "ACTIVE" state for callouts has gone away. There
is now only "PENDING" (scheduled to fire in the future) and "EXPIRED"
(has fired, and the function called).

Kernel version bump not done; we'll ride the 1.6N bump that happened
with the malloc(9) change.

Zombie procs have no lwps.

Merge the nathanw_sa branch.

branches: 1.17.2;
Casting from a pointer, to a db_expr_t, has to go via an intptr_t.
(db_expr_t == int64_t on sh5, for example).

branches: 1.16.8;
ANSIfy, KNF.
Make some variables and functions static when not used outside of a module.
Make variables in headers extern.
Delete the unused db_find_watchpoint() function.

add RCSIDs

use a for loop instead of goto.

Optimization suggested by Bill Sommerfeld: Keep a hint as to the
"earliest" firing callout in a bucket. This allows us to skip
the scan up the bucket if no callouts are due in the bucket.

A cheap O(1) hint update is done at callout insertion (if new callout
is earlier than hint) and removal (is bucket empty). A thorough
refresh of the hint is done when the bucket is traversed.

This doesn't matter much on machines with small values of hz
(e.g. i386), but on systems with large values of hz (e.g. Alpha),
it has a definite positive effect.

Also, keep the callwheel stats in evcnts, so that you can view them
with "vmstat -e".

branches: 1.12.2;
Add an easy way to dump the message buffer from ddb.

branches: 1.11.2; 1.11.4;
Make sure values for a %llx are long long.

Implement db_show_callout() again.

Interface change: db_printsym() takes a third argument, pr, a function
pointer indicating how to print the symbol. This allows db_printsym()
to called in places where db_printf() is not an appropriate output
function.

While straightforward, apologies in advance if I've introduced any minor
syntax errors; I was unable to test compilation this on all the affected
platforms.

Cast timeval members to types we know the printf conversions of.

New callout mechanism with two major improvements over the old
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.

The old timeout()/untimeout() API has been removed from the kernel.

branches: 1.6.2;
XXX LOCKING XXX of allproc; DDB runs with interrupts blocked, and MD
code should suspend other processors, so this probably isn't a problem,
but the comment is added anyhow.

branches: 1.5.8;
- Use proclists[], rather than checking allproc and zombproc explicitly.
- Add some comments about locking.

Merge paddr_t changes into the main branch.

branches: 1.3.2;
Print more info on ps/w, note the current proc, and properly declare db_maxoff.

fix printf formatting of "ps" (aka "show all proc") so that lines never
overflow (always hated that).

replaced "/m" flag with:
/a == show process address info
/n == show normal process info [currently the default]
/w == show process wait/emul info

Move some DDB stuff here from kern_clock.c and kern_proc.c

For architectures (mips64) where sizeof(db_expr_t) != sizeof(kcondvar_t *)
cast through uintptr_t.

Add some simple DDB show commands: condvar, selinfo, sleepq

Move proc_lock into the data segment. It was dynamically allocated because
at the time we had mutex_obj_alloc() but not __cacheline_aligned.

Make the db_kernelonly() macro visible to all files and re-use it.
Register access is kernel only.

Load struct fdfile::ff_file with atomic_load_consume.

Exceptions: when we're only testing whether it's there, not about to
dereference it.

Note: We do not use atomic_store_release to set it because the
preceding mutex_exit should be enough.

(That said, it's not clear the mutex_enter/exit is needed unless
refcnt > 0 already, in which case maybe it would be a win to switch
from the membar implied by mutex_enter to the membar implied by
atomic_store_release -- which I would generally expect to be much
cheaper. And a little clearer without a long comment.)

Load struct filedesc::fd_dt with atomic_load_consume.

Exceptions: when fd_refcnt <= 1, or when holding fd_lock.

While here:

- Restore KASSERT(mutex_owned(&fdp->fd_lock)) in fd_unused.
=> This is used only in fd_close and fd_abort, where it holds.
- Move bounds check assertion in fd_putfile to where it matters.
- Store fd_dt with atomic_store_release.
- Move load of fd_dt under lock in knote_fdclose.
- Omit membar_consumer in fdesc_readdir.
=> atomic_load_consume serves the same purpose now.
=> Was needed only on alpha anyway.

branches: 1.71.18; 1.71.24;
Don't use an unset value as an address

Instead, show usage if no address is passed.

branches: 1.70.2;
Try not to use f_data, use f_{vnode,socket,pipe,mqueue,kqueue,ksem} to get
a correctly typed pointer.

remove previous, dmesg just works.

Add "show dmesg" that prints the contents of the message buffer.

Add "show panic" that shows the current panic string. two ports had it, and
it could be easily made MI.

branches: 1.66.8;
If we are DIAGNOSTIC don't try to go further if we failed to take the
lock, because we are going to trigger a KASSERT. Also hold the lock
longer and take the proc lock for kpsignal(). Maybe we should add
mutex_steal() and mutex_return() for the debugger? Lock correction
suggestion from jmcneill.

deal with the proc_lock mutex.

branches: 1.64.2;
Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.

branches: 1.63.2;
re-instate db_kill_proc

branches: 1.62.4; 1.62.6;
Add #ifdef MQUEUE for db_show_mqueue_cmd().

XXX: Wrong. DDB should be dynamic, modular, etc.

More changes to improve kern_descrip.c.

- Avoid atomics in more places.
- Remove the per-descriptor mutex, and just use filedesc_t::fd_lock.
It was only being used to synchronize close, and in any case we needed
to take fd_lock to free the descriptor slot.
- Optimize certain paths for the <NDFDFILE case.
- Sprinkle more comments and assertions.
- Cache more stuff in filedesc_t.
- Fix numerous minor bugs spotted along the way.
- Restructure how the open files array is maintained, for clarity and so
that we can eliminate the membar_consumer() call in fd_getfile(). This is
mostly syntactic sugar; the main functional change is that fd_nfiles now
lives alongside the open file array.

Some measurements with libmicro:

- simple file syscalls are like close() are between 1 to 10% faster.
- some nice improvements, e.g. poll(1000) which is ~50% faster.

Make 'show event', 'dmesg' work with crash(8).
XXX dmesg fails exactly the same way as /sbin/dmesg.

include <stdbool.h> if not _KERNEL, and don't include kauth.h if _KERNEL.

now crash builds on i386.

include ddb headers *after* sys/types.h or sys/param.h.

Make ddb compile and work in userspace. Mostly this is comprised of three
types of changes:

- Add a few new methods to replace stuff like p_find(), CPU_INFO_FOREACH.

- Use db_read_bytes() instead of accessing kernel structures directly,
and similar changes.

- Add ifdef _KERNEL where the above hasn't been done, and an XXX comment.

- fix vmem unittest. rename VMEM_DEBUG so that it won't be abused again.
- reimplement vmem sanity checks with less code duplication.
- reimplement ddb vmem-related commands in a more consistent ways.
remove automatic whatis.

branches: 1.55.2;
Default 'show all procs' to /l. People tend to type 'ps' without modifiers
when providing information about deadlocks. Without the thread info it's
not very useful.

Add some basic DDB stuff for modules.

ifdef AIO

branches: 1.52.2; 1.52.4;
Replace more intptr_t to uintptr_t when casting VA.

Take care not to dereference NULL datapointer from fd table
Make output more readable and label what lock we are examining.

Fix indents.

Add a show files command that prints the vnodes associated with a
given struct proc and, if LOCKDEBUG is built in, the lock status of
the uvmobject.

branches: 1.48.14; 1.48.18; 1.48.20; 1.48.22; 1.48.24;
ps/w: display LWP info.

branches: 1.47.6;
Implementation of POSIX message queues.

Reviewed by: <ad>, <tech-kern>

branches: 1.46.4; 1.46.6; 1.46.8;
include cdefs.h before opt_xxx.h

branches: 1.45.2;
Merge some of the less invasive changes from the vmlocking branch:

- kthread, callout, devsw API changes
- select()/poll() improvements
- miscellaneous MT safety improvements

merge yamt-idlelwp branch. asked by core@. some ports still needs work.

from doc/BRANCHES:

idle lwp, and some changes depending on it.

1. separate context switching and thread scheduling.
(cf. gmcgarry_ctxsw)
2. implement idle lwp.
3. clean up related MD/MI interfaces.
4. make scheduler(s) modular.

Import of POSIX Asynchronous I/O.
Seems to be quite stable. Some work still left to do.

Please note, that syscalls are not yet MP-safe, because
of the file and vnode subsystems.

Reviewed by: <tech-kern>, <ad>

branches: 1.42.4; 1.42.6;
Fix lossage from boolean_t -> bool and updated x86 bus_dma.

branches: 1.41.2;
Merge newlock2 to head.

__unused removal on arguments; approved by core.

- sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386

branches: 1.38.8; 1.38.10;
integrate kauth.

branches: 1.37.2; 1.37.4; 1.37.6; 1.37.8; 1.37.10;
db_show_sched_qs: fix pointer cast lint considers troublesome.

Add /l to show all procs usage.

This is not IOCCC. Replace " >"[cp == p] with conditional expression.
Makes lint happy. Probably generates better code too (does on sh3).

branches: 1.34.2;
After addition of "show all pools", we now need <sys/pool.h> here.
Fixes build problem for mac68k.

add "show all pools" command for ddb.

- change the way to specify a bufq strategy. (by string rather than by number)
- rather than embedding bufq_state in driver softc,
have a pointer to the former.
- move bufq related functions from kern/subr_disk.c to kern/subr_bufq.c.
- rename method to strategy for consistency.
- move some definitions which don't need to be exposed to the rest of kernel
from sys/bufq.h to sys/bufq_impl.h.
(is it better to move it to kern/ or somewhere?)
- fix some obvious breakage in dev/qbus/ts.c. (not tested)

branches: 1.31.2;
more constification fallout

nuke trailing whitespace

branches: 1.29.4; 1.29.6;
Make ddb's "show sched_qs" aware of big-endian sched_qs arrangements.

Add a "show sched_qs" command to dump the run queues. Format is:
1 pid.lid (p_comm)
pid.lid (p_comm)
...

If a queue has procs, but no sched_whichqs bit, it shows:
!1 pid.lid (p_comm)

Widen FLAGS column for ps/l so that all defined l_flag flags fit.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.25.2;
Allow the dmesg command to show the last N bytes of the kernel message
buffer.

Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

(1) Don't print the message buffer (via ddb's dmesg command) if the
message buffer has not yet been set up, mimicking code from the top of
the sysctl routine for retrieving the message buffer.

(2) Add a /l modifier to the trace command. This makes it print the
backtrace using printf() instead of db_printf(), which has the nice
side-effect of also putting it into the message buffer. A kernel with
ddb in it but disabled (ie, ddb.onpanic set to zero) will print a
backtrace (which ends up in the message buffer) before dumping (or
not, depending on the value of kern.dump_on_panic) and rebooting, but
if ddb is not disabled, the backtrace is not printed, and there's no
way to get it to display a backtrace such that you can retrieve it
after the dump. The backtrace printed by gdb is sometimes a little
different.

(3) Documentation for the above.

Add a rudimentary 'trap to kgdb' command if KGDB is defined. This allows
systems with only one serial port for console, etc., to have at least some
basic access to remote-kgdb-over-serial, even if it is a bit awkward.

New callout implementation. This is based on callwheel implementation
done by Artur Grabowski and Thomas Nordin for OpenBSD, which is more
efficient in several ways than the callwheel implementation that it is
replacing. It has been adapted to our pre-existing callout API, and
also provides the slightly more efficient (and much more intuitive)
API (adapted to the callout_*() naming scheme) that the OpenBSD version
provides.

Among other things, this shaves a bunch of cycles off rescheduling-in-
the-future a callout which is already scheduled, which the common case
for TCP timers (notably REXMT and KEEP).

The API has been simplified a bit, as well. The (very confusing to
a good many people) "ACTIVE" state for callouts has gone away. There
is now only "PENDING" (scheduled to fire in the future) and "EXPIRED"
(has fired, and the function called).

Kernel version bump not done; we'll ride the 1.6N bump that happened
with the malloc(9) change.

Zombie procs have no lwps.

Merge the nathanw_sa branch.

branches: 1.17.2;
Casting from a pointer, to a db_expr_t, has to go via an intptr_t.
(db_expr_t == int64_t on sh5, for example).

branches: 1.16.8;
ANSIfy, KNF.
Make some variables and functions static when not used outside of a module.
Make variables in headers extern.
Delete the unused db_find_watchpoint() function.

add RCSIDs

use a for loop instead of goto.

Optimization suggested by Bill Sommerfeld: Keep a hint as to the
"earliest" firing callout in a bucket. This allows us to skip
the scan up the bucket if no callouts are due in the bucket.

A cheap O(1) hint update is done at callout insertion (if new callout
is earlier than hint) and removal (is bucket empty). A thorough
refresh of the hint is done when the bucket is traversed.

This doesn't matter much on machines with small values of hz
(e.g. i386), but on systems with large values of hz (e.g. Alpha),
it has a definite positive effect.

Also, keep the callwheel stats in evcnts, so that you can view them
with "vmstat -e".

branches: 1.12.2;
Add an easy way to dump the message buffer from ddb.

branches: 1.11.2; 1.11.4;
Make sure values for a %llx are long long.

Implement db_show_callout() again.

Interface change: db_printsym() takes a third argument, pr, a function
pointer indicating how to print the symbol. This allows db_printsym()
to called in places where db_printf() is not an appropriate output
function.

While straightforward, apologies in advance if I've introduced any minor
syntax errors; I was unable to test compilation this on all the affected
platforms.

Cast timeval members to types we know the printf conversions of.

New callout mechanism with two major improvements over the old
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.

The old timeout()/untimeout() API has been removed from the kernel.

branches: 1.6.2;
XXX LOCKING XXX of allproc; DDB runs with interrupts blocked, and MD
code should suspend other processors, so this probably isn't a problem,
but the comment is added anyhow.

branches: 1.5.8;
- Use proclists[], rather than checking allproc and zombproc explicitly.
- Add some comments about locking.

Merge paddr_t changes into the main branch.

branches: 1.3.2;
Print more info on ps/w, note the current proc, and properly declare db_maxoff.

fix printf formatting of "ps" (aka "show all proc") so that lines never
overflow (always hated that).

replaced "/m" flag with:
/a == show process address info
/n == show normal process info [currently the default]
/w == show process wait/emul info

Move some DDB stuff here from kern_clock.c and kern_proc.c

For architectures (mips64) where sizeof(db_expr_t) != sizeof(kcondvar_t *)
cast through uintptr_t.

Add some simple DDB show commands: condvar, selinfo, sleepq

Move proc_lock into the data segment. It was dynamically allocated because
at the time we had mutex_obj_alloc() but not __cacheline_aligned.

Make the db_kernelonly() macro visible to all files and re-use it.
Register access is kernel only.

Load struct fdfile::ff_file with atomic_load_consume.

Exceptions: when we're only testing whether it's there, not about to
dereference it.

Note: We do not use atomic_store_release to set it because the
preceding mutex_exit should be enough.

(That said, it's not clear the mutex_enter/exit is needed unless
refcnt > 0 already, in which case maybe it would be a win to switch
from the membar implied by mutex_enter to the membar implied by
atomic_store_release -- which I would generally expect to be much
cheaper. And a little clearer without a long comment.)

Load struct filedesc::fd_dt with atomic_load_consume.

Exceptions: when fd_refcnt <= 1, or when holding fd_lock.

While here:

- Restore KASSERT(mutex_owned(&fdp->fd_lock)) in fd_unused.
=> This is used only in fd_close and fd_abort, where it holds.
- Move bounds check assertion in fd_putfile to where it matters.
- Store fd_dt with atomic_store_release.
- Move load of fd_dt under lock in knote_fdclose.
- Omit membar_consumer in fdesc_readdir.
=> atomic_load_consume serves the same purpose now.
=> Was needed only on alpha anyway.

branches: 1.71.18; 1.71.24;
Don't use an unset value as an address

Instead, show usage if no address is passed.

branches: 1.70.2;
Try not to use f_data, use f_{vnode,socket,pipe,mqueue,kqueue,ksem} to get
a correctly typed pointer.

remove previous, dmesg just works.

Add "show dmesg" that prints the contents of the message buffer.

Add "show panic" that shows the current panic string. two ports had it, and
it could be easily made MI.

branches: 1.66.8;
If we are DIAGNOSTIC don't try to go further if we failed to take the
lock, because we are going to trigger a KASSERT. Also hold the lock
longer and take the proc lock for kpsignal(). Maybe we should add
mutex_steal() and mutex_return() for the debugger? Lock correction
suggestion from jmcneill.

deal with the proc_lock mutex.

branches: 1.64.2;
Welcome to 5.99.53! Merge rmind-uvmplock branch:

- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.

- Simplify locking in some pmap(9) modules by removing P->V locking.

- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).

- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.

- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.

Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.

branches: 1.63.2;
re-instate db_kill_proc

branches: 1.62.4; 1.62.6;
Add #ifdef MQUEUE for db_show_mqueue_cmd().

XXX: Wrong. DDB should be dynamic, modular, etc.

More changes to improve kern_descrip.c.

- Avoid atomics in more places.
- Remove the per-descriptor mutex, and just use filedesc_t::fd_lock.
It was only being used to synchronize close, and in any case we needed
to take fd_lock to free the descriptor slot.
- Optimize certain paths for the <NDFDFILE case.
- Sprinkle more comments and assertions.
- Cache more stuff in filedesc_t.
- Fix numerous minor bugs spotted along the way.
- Restructure how the open files array is maintained, for clarity and so
that we can eliminate the membar_consumer() call in fd_getfile(). This is
mostly syntactic sugar; the main functional change is that fd_nfiles now
lives alongside the open file array.

Some measurements with libmicro:

- simple file syscalls are like close() are between 1 to 10% faster.
- some nice improvements, e.g. poll(1000) which is ~50% faster.

Make 'show event', 'dmesg' work with crash(8).
XXX dmesg fails exactly the same way as /sbin/dmesg.

include <stdbool.h> if not _KERNEL, and don't include kauth.h if _KERNEL.

now crash builds on i386.

include ddb headers *after* sys/types.h or sys/param.h.

Make ddb compile and work in userspace. Mostly this is comprised of three
types of changes:

- Add a few new methods to replace stuff like p_find(), CPU_INFO_FOREACH.

- Use db_read_bytes() instead of accessing kernel structures directly,
and similar changes.

- Add ifdef _KERNEL where the above hasn't been done, and an XXX comment.

- fix vmem unittest. rename VMEM_DEBUG so that it won't be abused again.
- reimplement vmem sanity checks with less code duplication.
- reimplement ddb vmem-related commands in a more consistent ways.
remove automatic whatis.

branches: 1.55.2;
Default 'show all procs' to /l. People tend to type 'ps' without modifiers
when providing information about deadlocks. Without the thread info it's
not very useful.

Add some basic DDB stuff for modules.

ifdef AIO

branches: 1.52.2; 1.52.4;
Replace more intptr_t to uintptr_t when casting VA.

Take care not to dereference NULL datapointer from fd table
Make output more readable and label what lock we are examining.

Fix indents.

Add a show files command that prints the vnodes associated with a
given struct proc and, if LOCKDEBUG is built in, the lock status of
the uvmobject.

branches: 1.48.14; 1.48.18; 1.48.20; 1.48.22; 1.48.24;
ps/w: display LWP info.

branches: 1.47.6;
Implementation of POSIX message queues.

Reviewed by: <ad>, <tech-kern>

branches: 1.46.4; 1.46.6; 1.46.8;
include cdefs.h before opt_xxx.h

branches: 1.45.2;
Merge some of the less invasive changes from the vmlocking branch:

- kthread, callout, devsw API changes
- select()/poll() improvements
- miscellaneous MT safety improvements

merge yamt-idlelwp branch. asked by core@. some ports still needs work.

from doc/BRANCHES:

idle lwp, and some changes depending on it.

1. separate context switching and thread scheduling.
(cf. gmcgarry_ctxsw)
2. implement idle lwp.
3. clean up related MD/MI interfaces.
4. make scheduler(s) modular.

Import of POSIX Asynchronous I/O.
Seems to be quite stable. Some work still left to do.

Please note, that syscalls are not yet MP-safe, because
of the file and vnode subsystems.

Reviewed by: <tech-kern>, <ad>

branches: 1.42.4; 1.42.6;
Fix lossage from boolean_t -> bool and updated x86 bus_dma.

branches: 1.41.2;
Merge newlock2 to head.

__unused removal on arguments; approved by core.

- sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386

branches: 1.38.8; 1.38.10;
integrate kauth.

branches: 1.37.2; 1.37.4; 1.37.6; 1.37.8; 1.37.10;
db_show_sched_qs: fix pointer cast lint considers troublesome.

Add /l to show all procs usage.

This is not IOCCC. Replace " >"[cp == p] with conditional expression.
Makes lint happy. Probably generates better code too (does on sh3).

branches: 1.34.2;
After addition of "show all pools", we now need <sys/pool.h> here.
Fixes build problem for mac68k.

add "show all pools" command for ddb.

- change the way to specify a bufq strategy. (by string rather than by number)
- rather than embedding bufq_state in driver softc,
have a pointer to the former.
- move bufq related functions from kern/subr_disk.c to kern/subr_bufq.c.
- rename method to strategy for consistency.
- move some definitions which don't need to be exposed to the rest of kernel
from sys/bufq.h to sys/bufq_impl.h.
(is it better to move it to kern/ or somewhere?)
- fix some obvious breakage in dev/qbus/ts.c. (not tested)

branches: 1.31.2;
more constification fallout

nuke trailing whitespace

branches: 1.29.4; 1.29.6;
Make ddb's "show sched_qs" aware of big-endian sched_qs arrangements.

Add a "show sched_qs" command to dump the run queues. Format is:
1 pid.lid (p_comm)
pid.lid (p_comm)
...

If a queue has procs, but no sched_whichqs bit, it shows:
!1 pid.lid (p_comm)

Widen FLAGS column for ps/l so that all defined l_flag flags fit.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.25.2;
Allow the dmesg command to show the last N bytes of the kernel message
buffer.

Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

(1) Don't print the message buffer (via ddb's dmesg command) if the
message buffer has not yet been set up, mimicking code from the top of
the sysctl routine for retrieving the message buffer.

(2) Add a /l modifier to the trace command. This makes it print the
backtrace using printf() instead of db_printf(), which has the nice
side-effect of also putting it into the message buffer. A kernel with
ddb in it but disabled (ie, ddb.onpanic set to zero) will print a
backtrace (which ends up in the message buffer) before dumping (or
not, depending on the value of kern.dump_on_panic) and rebooting, but
if ddb is not disabled, the backtrace is not printed, and there's no
way to get it to display a backtrace such that you can retrieve it
after the dump. The backtrace printed by gdb is sometimes a little
different.

(3) Documentation for the above.

Add a rudimentary 'trap to kgdb' command if KGDB is defined. This allows
systems with only one serial port for console, etc., to have at least some
basic access to remote-kgdb-over-serial, even if it is a bit awkward.

New callout implementation. This is based on callwheel implementation
done by Artur Grabowski and Thomas Nordin for OpenBSD, which is more
efficient in several ways than the callwheel implementation that it is
replacing. It has been adapted to our pre-existing callout API, and
also provides the slightly more efficient (and much more intuitive)
API (adapted to the callout_*() naming scheme) that the OpenBSD version
provides.

Among other things, this shaves a bunch of cycles off rescheduling-in-
the-future a callout which is already scheduled, which the common case
for TCP timers (notably REXMT and KEEP).

The API has been simplified a bit, as well. The (very confusing to
a good many people) "ACTIVE" state for callouts has gone away. There
is now only "PENDING" (scheduled to fire in the future) and "EXPIRED"
(has fired, and the function called).

Kernel version bump not done; we'll ride the 1.6N bump that happened
with the malloc(9) change.

Zombie procs have no lwps.

Merge the nathanw_sa branch.

branches: 1.17.2;
Casting from a pointer, to a db_expr_t, has to go via an intptr_t.
(db_expr_t == int64_t on sh5, for example).

branches: 1.16.8;
ANSIfy, KNF.
Make some variables and functions static when not used outside of a module.
Make variables in headers extern.
Delete the unused db_find_watchpoint() function.

add RCSIDs

use a for loop instead of goto.

Optimization suggested by Bill Sommerfeld: Keep a hint as to the
"earliest" firing callout in a bucket. This allows us to skip
the scan up the bucket if no callouts are due in the bucket.

A cheap O(1) hint update is done at callout insertion (if new callout
is earlier than hint) and removal (is bucket empty). A thorough
refresh of the hint is done when the bucket is traversed.

This doesn't matter much on machines with small values of hz
(e.g. i386), but on systems with large values of hz (e.g. Alpha),
it has a definite positive effect.

Also, keep the callwheel stats in evcnts, so that you can view them
with "vmstat -e".

branches: 1.12.2;
Add an easy way to dump the message buffer from ddb.

branches: 1.11.2; 1.11.4;
Make sure values for a %llx are long long.

Implement db_show_callout() again.

Interface change: db_printsym() takes a third argument, pr, a function
pointer indicating how to print the symbol. This allows db_printsym()
to called in places where db_printf() is not an appropriate output
function.

While straightforward, apologies in advance if I've introduced any minor
syntax errors; I was unable to test compilation this on all the affected
platforms.

Cast timeval members to types we know the printf conversions of.

New callout mechanism with two major improvements over the old
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.

The old timeout()/untimeout() API has been removed from the kernel.

branches: 1.6.2;
XXX LOCKING XXX of allproc; DDB runs with interrupts blocked, and MD
code should suspend other processors, so this probably isn't a problem,
but the comment is added anyhow.

branches: 1.5.8;
- Use proclists[], rather than checking allproc and zombproc explicitly.
- Add some comments about locking.

Merge paddr_t changes into the main branch.

branches: 1.3.2;
Print more info on ps/w, note the current proc, and properly declare db_maxoff.