cvs commit: src/sys/i386/i386 pmap.c

[Jacques A. Vidrine]

On Tue, Oct 07, 2003 at 05:34:37AM -0700, Jacques A. Vidrine wrote:
> nectar      2003/10/07 05:34:37 PDT
> 
>   FreeBSD src repository
> 
>   Modified files:        (Branch: RELENG_4)
>     sys/i386/i386        pmap.c 
>   Log:
>   Disable PSE at boot time for Pentium 4 processors.  On many such CPUs,
>   data corruption will result otherwise.  It seems that the bug is
>   aggravated by recent work related to PAE.
>   
>   This change was originally based on rev 1.386, but now the test for
>   CPU type is correct and the display of the warning is postponed until
>   we have initialized the kernel message buffer (e.g. for dmesg).
>   
>   peter@ believes that only certain revisions of the Pentium 4 processor
>   are affected.  However, we are unsure which so we choose to be safe by
>   disabling PSE on all Pentium 4s.
>   
>   The test can be disabled entirely with NO_PSE_HACK.
>   
>   Approved by:    re
>   
>   Revision    Changes    Path
>   1.250.2.22  +34 -0     src/sys/i386/i386/pmap.c

The symptoms from this bug that I experienced on an ``Intel(R)
Celeron(R) CPU 2.00GHz'' system were SIGBUS and SIGSEGV during `make
buildworld'.

Cheers,
-- 
Jacques Vidrine   . NTT/Verio SME      . FreeBSD UNIX       . Heimdal
nectar at celabo.org . jvidrine at verio.net . nectar at freebsd.org . nectar at kth.se