holding CPU along with the lock. When a CPU fails to get the lock
it compares its own id to the holder id. If they are the same it
panic()s, as simple locks are binary, and this would cause a deadlock.
Controlled by smptests.h: SL_DEBUG, ON by default.
Some minor cleanup.
Add a simplelock to deal with disable_intr()/enable_intr() as used in UP kernel.
UP kernel expects that this is enough to guarantee exclusive access to
regions of code bracketed by these 2 functions.
Add a simplelock to bracket clock accesses in clock.c: clock_lock.
Help from: Bruce Evans <bde@zeta.org.au>
and the sound driver which uses auto dma.
The dma interface functionality remains however it now checks
to see if a dma is operating in auto dma mode and if so it bypasses
the busy flag check . I have modified the sound driver 3.5 to
adjust for this new behavior and tested it under FreeBSD 3.0 -current
This patch also includes the new function isa_dmastop.
Submitted by: Amancio Hasty <hasty@rah.star-gate.com>
smp_active = 1 used to indicate that the system had frozen previously
started AP's, while smp_active = 0 was "AP's not yet started". I have split
this into smp_started (which is set when the AP's come online), and
smp_active is left for turning on/off AP scheduling.
- We now have enough per-cpu idle context, the real idle loop has been
revived (cpu's halt now with nothing to do).
- Some preliminary support for running some operations outside the
global lock (eg: zeroing "free but not yet zeroed pages") is present
but appears to cause problems. Off by default.
- the smp_active sysctl now behaves differently. It's merely a 'true/false'
option. Setting smp_active to zero causes the AP's to halt in the idle
loop and stop scheduling processes.
- bootstrap is a lot safer. Instead of sharing a statically compiled in
stack a number of times (which has caused lots of problems) and then
abandoning it, we use the idle context to boot the AP's directly. This
should help >2 cpu support since the bootlock stuff was in doubt.
- print physical apic id in traps.. helps identify private pages getting
out of sync. (You don't want to know how much hair I tore out with this!)
More cleanup to follow, this is more of a checkpoint than a
'finished' thing.
irqs can't work (at best, the first one attached wins). It used to
be necessary to skip this check because of bogus irqs in the sound
drivers, but the sound drivers have been fixed, except possibly the
OSS ones.
wasted.
Fixed type mismatches for functions with vm_prot_t's as args. vm_prot_t
is u_char, so the prototypes should have used promoteof(u_char) to match
the old-style function definitions. They use just vm_prot_t. This depends
on gcc features to work. I fixed the definitions since this is easiest.
The correct fix may be to change vm_prot_t to u_int, to optimize for time
instead of space.
Removed a stale comment.
Added a new variable, 'bsp_apic_ready', which is set as soon as the bootstrap
CPU has initialized its local APIC. Conditionalize the GENSPLR functions
to call ss_lock ONLY after bsp_apic_ready is TRUE; This should prevent
any problems with races between the time the 1st AP becomes ready and the
time smp_active is set.
region protected by the simplelock 'cpl_lock'.
Notes:
- this code is currently controlled on a section by section basis with
defines in machine/param.h. All sections are currently enabled.
- this code is not as clean as I would like, but that can wait till later.
- the "giant lock" still surrounds most instances of this "cpl region".
I still have to do the code that arbitrates setting cpl between the
top and bottom halves of the kernel.
- the possibility of deadlock exists, I am committing the code at this
point so as to exercise it and detect any such cases B4 the "giant lock"
is removed.
Made NEW_STRATEGY default.
Removed misc. old cruft.
Centralized simple locks into mp_machdep.c
Centralized simple lock macros into param.h
More cleanup in the direction of making splxx()/cpl MP-safe.
Several new fine-grained locks.
New FAST_INTR() methods:
- separate simplelock for FAST_INTR, no more giant lock.
- FAST_INTR()s no longer checks ipending on way out of ISR.
sio made MP-safe (I hope).
We now tsleep() in kthread_init() between start_init()
and prepare_usermode() while waiting for ALL the idle_loop()
processes to come online.
Debugged & tested by: "Thomas D. Dean" <tomdean@ix.netcom.com>
Reviewed by: David Greenman <dg@root.com>
as chargeable CPU usage. This should mitigate the problem of processes
doing disk I/O hogging the CPU. Various users have reported the
problem, and test code shows that the problem should now be gone.
Work done by BSDI, Jonathan Lemon <jlemon@americantv.com>,
Mike Smith <msmith@gsoft.com.au>, Sean Eric Fagan <sef@kithrup.com>,
and probably alot of others.
Submitted by: Jnathan Lemon <jlemon@americantv.com>
This code was eliminated when the PEND_INTS algorithm was added. But it was
discovered that PEND_INTS only worsen latency for FAST_INTR() routines,
which can't be marked pending.
Noticed & debugged by: dave adkins <adkin003@gold.tc.umn.edu>
Initially functionality is confined to 32-bit BIOS functions, however
it is envisioned that BIOS support may be enlisted for other
activities in the future.
