2. Update a comment. We now restore much more than RTC updates and
interrupts.
3. Order change. Stop interrupts by writing to RTC_STATUSB,
restore rate bits for the interrupts by writing to RTC_STATUSA,
then enable interrupts again.
This seems to be done perfectly backwards in startrtclock().
Otherwise, the idea for this change was obtained from
startrtclock().
4. Don't stop the clock (RTCB_HALT). We only program some control bits
and don't want to stop the clock.
5. (Not really related.) Add caveats to the comment about timer_restore().
The update is non-atomic since locking is not done.
On locking:
6. rtcin() and writertc() are locked() adequately by splhigh() in RELENG_4,
but this locking is null in -current.
7. Doing things in the correct order in (3) combined with (6) is probably
enough locking for rtcrestore() in RELENG_4. In -current, the
writertc()'s race with rtcintr() unless the BIOS disables RTC interrupts.
Submitted by: bde (including commit message)
MFC after: 1 week
homerolling our own version.
- Rename the enum for memsize from ISA_IVAR_MSIZE to ISA_IVAR_MEMSIZE
since using 'MSIZE' in the macro invocation of ISA_ACCESSOR() conflicts
with the 'MSIZE' kernel option. The accessor function is still
isa_get_msize().
Rename diskerr() to disk_err() for naming consistency.
Drop the by now entirely useless struct disklabel argument.
Add a flag argument for new-line termination.
Fix a couple of printf-format-casts to %j instead of %l.
Correctly print the name of all bio commands.
Move the function from subr_disklabel.c to subr_disk.c,
and from <sys/disklabel.h> to <sys/disk.h>.
Use the new disk_err() throughout, #include <sys/disk.h> as needed.
Bump __FreeBSD_version for the sake of the aac disk drivers #ifdefs.
Remove unused disklabel members of softc for aac, amr and mlx, which seem
to originally have been intended for diskerr() use, but which only rotted
and got Copy&Pasted at least two times to many.
Sponsored by: DARPA & NAI Labs.
when machdep.tsc_freq returned a negative number on a 2.2GHz Xeon.
Submitted by: Brian Harrison <bharrison@ironport.com>
Reviewed by: phk
MFC after: 1 week
previously used "micro-optimization" (count-down loop) into a
pessimization. Now the loops are written in the more natural count-up
form.
Also, while being there, i made the logic in out_fdc() similar to the
logic in in_fdc(). The old implementation was a bit bogus anyway
since it first tested the DIO bit and only afterwards the RQM bit.
However, according to the description of the i82077, the DIO bit is
only guaranteed to be valid once the RQM bit is set. Thus, the old
implementatoin would have had the chance to misbehave on a controller
that is implemented in accordance with the i82077 description (but is
not bug-for-bug compatible).
MFC after: 3 days
before rev 1.229 (~ 100 ms). According to bde, some (old) broken
hardware could require it. In order to make timing more accurate than
what could be achieved with a loop around DELAY(1), increase loop
timing after the initial ~ 1 ms.
Also, move the declaration of FDSTS_TIMEOUT out from fdreg.h into fd.c
where it actually belongs to.
MFC after: 2 days
in each cycle, with a tunable max cycle count defined in fdreg.h.
This is said to fix the problem on some Compaq hardware (and perhaps
on other machines using the Natsemi PC87317 chip) where the fdc(4)
driver failed to operate at all.
PR: kern/21397
Submitted by: Jung-uk Kim <jkim@niksun.com>
MFC after: 3 days
timecounter will be used starting at the next second, which is
good enough for sysctl purposes. If better adjustment is needed
the NTP PLL should be used.
"raw partition" of any kind since the floppy driver doesn't support
UFS-style partitions at all.
Reported by: "Crist J. Clark" <crist.clark@attbi.com>
Reviewed by: bde
MFC after: 3 days
general cleanup of the API. The entire API now consists of two functions
similar to the pre-KSE API. The suser() function takes a thread pointer
as its only argument. The td_ucred member of this thread must be valid
so the only valid thread pointers are curthread and a few kernel threads
such as thread0. The suser_cred() function takes a pointer to a struct
ucred as its first argument and an integer flag as its second argument.
The flag is currently only used for the PRISON_ROOT flag.
Discussed on: smp@
disablement assumptions in kern_fork.c by adding another API call,
cpu_critical_fork_exit(). Cleanup the td_savecrit field by moving it
from MI to MD. Temporarily move cpu_critical*() from <arch>/include/cpufunc.h
to <arch>/<arch>/critical.c (stage-2 will clean this up).
Implement interrupt deferral for i386 that allows interrupts to remain
enabled inside critical sections. This also fixes an IPI interlock bug,
and requires uses of icu_lock to be enclosed in a true interrupt disablement.
This is the stage-1 commit. Stage-2 will occur after stage-1 has stabilized,
and will move cpu_critical*() into its own header file(s) + other things.
This commit may break non-i386 architectures in trivial ways. This should
be temporary.
Reviewed by: core
Approved by: core
Problem:
selwakeup required calling pfind which would cause lock order
reversals with the allproc_lock and the per-process filedesc lock.
Solution:
Instead of recording the pid of the select()'ing process into the
selinfo structure, actually record a pointer to the thread. To
avoid dereferencing a bad address all the selinfo structures that
are in use by a thread are kept in a list hung off the thread
(protected by sellock). When a selwakeup occurs the selinfo is
removed from that threads list, it is also removed on the way out
of select or poll where the thread will traverse its list removing
all the selinfos from its own list.
Problem:
Previously the PROC_LOCK was used to provide the mutual exclusion
needed to ensure proper locking, this couldn't work because there
was a single condvar used for select and poll and condvars can
only be used with a single mutex.
Solution:
Introduce a global mutex 'sellock' which is used to provide mutual
exclusion when recording events to wait on as well as performing
notification when an event occurs.
Interesting note:
schedlock is required to manipulate the per-thread TDF_SELECT
flag, however if given its own field it would not need schedlock,
also because TDF_SELECT is only manipulated under sellock one
doesn't actually use schedlock for syncronization, only to protect
against corruption.
Proc locks are no longer used in select/poll.
Portions contributed by: davidc
enabled in critical sections and streamline critical_enter() and
critical_exit().
This commit allows an architecture to leave interrupts enabled inside
critical sections if it so wishes. Architectures that do not wish to do
this are not effected by this change.
This commit implements the feature for the I386 architecture and provides
a sysctl, debug.critical_mode, which defaults to 1 (use the feature). For
now you can turn the sysctl on and off at any time in order to test the
architectural changes or track down bugs.
This commit is just the first stage. Some areas of the code, specifically
the MACHINE_CRITICAL_ENTER #ifdef'd code, is strictly temporary and will
be cleaned up in the STAGE-2 commit when the critical_*() functions are
moved entirely into MD files.
The following changes have been made:
* critical_enter() and critical_exit() for I386 now simply increment
and decrement curthread->td_critnest. They no longer disable
hard interrupts. When critical_exit() decrements the counter to
0 it effectively calls a routine to deal with whatever interrupts
were deferred during the time the code was operating in a critical
section.
Other architectures are unaffected.
* fork_exit() has been conditionalized to remove MD assumptions for
the new code. Old code will still use the old MD assumptions
in regards to hard interrupt disablement. In STAGE-2 this will
be turned into a subroutine call into MD code rather then hardcoded
in MI code.
The new code places the burden of entering the critical section
in the trampoline code where it belongs.
* I386: interrupts are now enabled while we are in a critical section.
The interrupt vector code has been adjusted to deal with the fact.
If it detects that we are in a critical section it currently defers
the interrupt by adding the appropriate bit to an interrupt mask.
* In order to accomplish the deferral, icu_lock is required. This
is i386-specific. Thus icu_lock can only be obtained by mainline
i386 code while interrupts are hard disabled. This change has been
made.
* Because interrupts may or may not be hard disabled during a
context switch, cpu_switch() can no longer simply assume that
PSL_I will be in a consistent state. Therefore, it now saves and
restores eflags.
* FAST INTERRUPT PROVISION. Fast interrupts are currently deferred.
The intention is to eventually allow them to operate either while
we are in a critical section or, if we are able to restrict the
use of sched_lock, while we are not holding the sched_lock.
* ICU and APIC vector assembly for I386 cleaned up. The ICU code
has been cleaned up to match the APIC code in regards to format
and macro availability. Additionally, the code has been adjusted
to deal with deferred interrupts.
* Deferred interrupts use a per-cpu boolean int_pending, and
masks ipending, spending, and fpending. Being per-cpu variables
it is not currently necessary to lock; bus cycles modifying them.
Note that the same mechanism will enable preemption to be
incorporated as a true software interrupt without having to
further hack up the critical nesting code.
* Note: the old critical_enter() code in kern/kern_switch.c is
currently #ifdef to be compatible with both the old and new
methodology. In STAGE-2 it will be moved entirely to MD code.
Performance issues:
One of the purposes of this commit is to enhance critical section
performance, specifically to greatly reduce bus overhead to allow
the critical section code to be used to protect per-cpu caches.
These caches, such as Jeff's slab allocator work, can potentially
operate very quickly making the effective savings of the new
critical section code's performance very significant.
The second purpose of this commit is to allow architectures to
enable certain interrupts while in a critical section. Specifically,
the intention is to eventually allow certain FAST interrupts to
operate rather then defer.
The third purpose of this commit is to begin to clean up the
critical_enter()/critical_exit()/cpu_critical_enter()/
cpu_critical_exit() API which currently has serious cross pollution
in MI code (in fork_exit() and ast() for example).
The fourth purpose of this commit is to provide a framework that
allows kernel-preempting software interrupts to be implemented
cleanly. This is currently used for two forward interrupts in I386.
Other architectures will have the choice of using this infrastructure
or building the functionality directly into critical_enter()/
critical_exit().
Finally, this commit is designed to greatly improve the flexibility
of various architectures to manage critical section handling,
software interrupts, preemption, and other highly integrated
architecture-specific details.
is not configured. Including <isa/isavar.h> when it is not used is
harmful as well as bogus, since it includes "isa_if.h" which is not
generated when isa is not configured.
This was fixed in 1999 but was broken by unconditionalizing PNPBIOS.
and it's associated state variables: icu_lock with the name "icu". This
renames the imen_mtx for x86 SMP, but also uses the lock to protect
access to the 8259 PIC on x86 UP. This also adds an appropriate lock to
the various Alpha chipsets which fixes problems with Alpha SMP machines
dropping interrupts with an SMP kernel.
