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

[Scott Long]

David Rhodus wrote:
> 
> 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
> 
> 

It might indeed be interesting to backport Bosko's work to 4.x.
However, we are too close to the 4.9 release to do it now.  Jacques'
work is recognised as a band-aid for now.

Scott