Date: Thu, 17 Oct 2002 06:55:44 -0700 (PDT) From: Mitsuru IWASAKI <iwasaki@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/i386/isa clock.c Message-ID: <200210171355.g9HDtjBt054703@repoman.freebsd.org>
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iwasaki 2002/10/17 06:55:44 PDT
Modified files:
sys/i386/isa clock.c
Log:
1. Fix a comment. Locking _is_ needed (but not done).
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
Revision Changes Path
1.190 +8 -12 src/sys/i386/isa/clock.c
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