- Attach a writable sysctl to bootverbose (debug.bootverbose) so it can be
toggled after boot.
- Move the printf of the version string to a SI_SUB_COPYRIGHT SYSINIT just
afer the display of the copyright message instead of doing it by hand in
three MD places.
registers better. Hold sched_lock not only for checking the flag but
also while performing the actual operation to ensure the process doesn't
get swapped out by another CPU while we the operation is being performed.
. FD_CLRERR clears the error counter, thus re-enables kernel error
printf()s,
. FD_GSTAT obtains the last FDC operation state, if any,
. FDOPT_NOERRLOG (temporarily) turns off kernel printf() floppy
error logging,
. FDOPT_NOERROR makes the kernel ignore an FDC error, thus can
enable the transfer of an erroneous sector to the user application
All options are being cleared on (last) close.
Prime consumer of the last features will be fdread(1), to be committed
shortly.
(FD_CLRERR should be wired into fdcontrol(8), but then fdcontrol(8)
needs a major rewrite anyway.)
If for some reason DEVFS is undesired, the "NODEVFS" option is
needed now.
Pending any significant issues, DEVFS will be made mandatory in
-current on july 1st so that we can start reaping the full
benefits of having it.
other "system" header files.
Also help the deprecation of lockmgr.h by making it a sub-include of
sys/lock.h and removing sys/lockmgr.h form kernel .c files.
Sort sys/*.h includes where possible in affected files.
OK'ed by: bde (with reservations)
been made machine independent and various other adjustments have been made
to support Alpha SMP.
- It splits the per-process portions of hardclock() and statclock() off
into hardclock_process() and statclock_process() respectively. hardclock()
and statclock() call the *_process() functions for the current process so
that UP systems will run as before. For SMP systems, it is simply necessary
to ensure that all other processors execute the *_process() functions when the
main clock functions are triggered on one CPU by an interrupt. For the alpha
4100, clock interrupts are delievered in a staggered broadcast fashion, so
we simply call hardclock/statclock on the boot CPU and call the *_process()
functions on the secondaries. For x86, we call statclock and hardclock as
usual and then call forward_hardclock/statclock in the MD code to send an IPI
to cause the AP's to execute forwared_hardclock/statclock which then call the
*_process() functions.
- forward_signal() and forward_roundrobin() have been reworked to be MI and to
involve less hackery. Now the cpu doing the forward sets any flags, etc. and
sends a very simple IPI_AST to the other cpu(s). AST IPIs now just basically
return so that they can execute ast() and don't bother with setting the
astpending or needresched flags themselves. This also removes the loop in
forward_signal() as sched_lock closes the race condition that the loop worked
around.
- need_resched(), resched_wanted() and clear_resched() have been changed to take
a process to act on rather than assuming curproc so that they can be used to
implement forward_roundrobin() as described above.
- Various other SMP variables have been moved to a MI subr_smp.c and a new
header sys/smp.h declares MI SMP variables and API's. The IPI API's from
machine/ipl.h have moved to machine/smp.h which is included by sys/smp.h.
- The globaldata_register() and globaldata_find() functions as well as the
SLIST of globaldata structures has become MI and moved into subr_smp.c.
Also, the globaldata list is only available if SMP support is compiled in.
Reviewed by: jake, peter
Looked over by: eivind
It might be more correct to make stathz as close as possible to 128,
but that would involve adding complexity to the clock intr path, which
I don't want to do.
saves 32 registers) to do on every context switch. This is only required
for SMP, so only do it there.
We should also look at moving the critical enter/exit out to the callers
structure. This field keeps track of how many levels deep we are nested
into the kernel. The nesting level is bumped at the start of a trap,
interrupt, syscall, or exception and is decremented on return. This is
used to detect the case when the kernel is returning back to a kernel
context in exception_return(). If we are returning to the kernel we need
to update the globaldata pointer register saved in the stack frame in case
we have switched CPU's between taking the initial interrupt that saved the
frame and returning. If we don't do this fixup it is possible for a CPU to
use the wrong per-cpu data. On UP systems this is not a problem, so the
code is conditional on SMP.
A count was used instead of simply checking the process status register in
the frame during exception_return() since there are critical sections at
the very start and end of a trap, exception, or interrupt from userland in
which we could trash the t7 register being used in userland. The counter
is incremented after adn before these critical sections respectively so
that we will not overwrite the saved t7 register if we are interrupted
during one of these critical sections.
This is will be required to prevent lowering the ipl when a critical_enter()
is present in the interrupt path when handling a machine check.
reviewed by: jhb
and AS4100s into single user mode. This work was done jointly by jhb and
myself, and builds on dfr's earlier work.
smp_init_secondary() / smp_start_secondary()
- use the uniq val to pass the globalp (me)
- fancy footwork to take any pending machine checks (me)
- doing things the FreeBSD way and getting the per-cpu idleproc created
correctly, and synchronizing the startup of secondaries (jhb)
mp_start()
- better recognition of available cpus (jhb)
smp_rendezvous()
- if smp hasn't started, only run the rendezvous function on the current
cpu. Sleuthing and (prior) incorrect fix by me, correct fix by jhb
smp_handle_ipi()
- more verbose handling of console messages (jhb)
- grab sched lock around setting PS_ASTPENDING (jhb)
forward_*clock()
- commented out. Joint decision by dfr, jhb and myself
General synchronization improvements (more mb()s, etc) (jhb)
Printf cleanups (joint)
Whitespace cleanups (jhb)
- don't do the stack overflow sanity check on MP systems -- p->p_addr
will be malloc'ed memory (not K0SEG) and the check will fail.
- don't ignore clock interrupts on secondaries. Alphas apparently
roundrobin clock interrupts to all cpus, so we're going to take clock
interrupts on all CPUS and not forward them.
- use the unique value to save the per-cpu globalp struct like the
comment says
- don't lower the ipl to ALPHA_PSL_IPL_HIGH: we may have a pending machine
check to take and we're not prepared for that yet, as we haven't setup
our interrupt entry points. (this may only happen on sable/lynx)
- indicate the fact that the working version of smp_init_secondary() doesn't
return (this is tied up in other changes and hasn't yet been committed).
panic_cpu shared variable. I used a simple atomic operation here instead
of a spin lock as it seemed to be excessive overhead. Also, this can avoid
recursive panics if, for example, witness is broken.
"inside" of locked regions. That is, an acquire atomic operation will
always enforce a memory barrier after the atomic operation and a release
operation will always enforce a memory barrier before the atomic
operation.
- Explicitly use 'mb' instead of 'wmb' in release atomic operations. The
'wmb' memory barrier is not strong enough to guarantee coherence with
other processors. This is effectively a nop since alpha_wmb() actually
performs a 'mb' and not a 'wmb', but I wanted the code to be more
correct since at some point in the future alpha_wmb()'s implementation
may switch to being a real 'wmb'.
we should call ast(). This allows us to branch to a separate Lkernelret
label so we can fixup the saved t7 register in the trapframe. Otherwise
we can run into a problem on SMP systems where a process is interrupted by
a trap or interrupt on one CPU, migrates to another CPU, and then returns
with the t7 in the stack clobbering the CPU's t7. As a result, two CPU's
would both point to the same per-CPU data and things would go downhill from
there.
Sleuthing help by: gallatin
- Add a new ddb command: 'show pcpu' similar to the i386 command added
recently. By default it displays the current CPU's info, but an optional
argument can specify the logical ID of a specific CPU to examine.
badaddr_read(). This fixes 'machine check in pal mode' halts on
ev5 2100As.
MFC candidate -- after spending 6 hours tracking this down, I checked and
discovered that it has been in NetBSD for over a year, so it should be safe
for MFC into 4.3-RELEASE
