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

[David Rhodus]

On Tuesday, October 7, 2003, at 08:53 AM, Jacques A. Vidrine wrote:

> 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'.

Interesting, I was just typing a message to ask if we needed to look at
applying bmilekic's work to RELENG_4. Is that being looked at as a
more elegant method rather than leaving PSE turned off.

-DR