From owner-cvs-all  Sat Dec 25  7:30:35 1999
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From: Bruce Evans <bde@FreeBSD.org>
Date: Sat, 25 Dec 1999 07:30:32 -0800 (PST)
To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: cvs commit: src/sys/i386/isa clock.c
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bde         1999/12/25 07:30:32 PST

  Modified files:
    sys/i386/isa         clock.c 
  Log:
  Fixed races accessing the RTC.  The races apparently caused
  apm_default_resume() to sometimes set a very wrong time.
  (1) Accesses to the RTC index and data registers were not atomic enough.
      Interrupts were not masked.  This was only good enough until an
      interrupt handler (rtcintr()) started accessing the RTC in FreeBSD-2.0.
  (2) Access to the block of time registers in inittodr() was not atomic
      enough.  inittodr() has 244us to read the time registers.  Interrupts
      were not masked.  This was only good enough until something (apm)
      started calling inittodr() after boot time in FreeBSD-2.0.
  The fix for (2) also makes the timecounter update more atomic, although
  this is currently unimportant due to the low resolution of the RTC.
  
  Problem reported by:	mckay
  
  Revision  Changes    Path
  1.148     +17 -5     src/sys/i386/isa/clock.c



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