MSR_SPE - being turned off...

[Morrison, Tom]

Ok...taken out...

>> -----Original Message-----
>> From: Kumar Gala [mailto:galak at kernel.crashing.org]
>> Sent: Tuesday, May 05, 2009 5:18 PM
>> To: Morrison, Tom
>> Cc: linuxppc-dev at ozlabs.org; Michael Neuling
>> Subject: Re: MSR_SPE - being turned off...
>> 
>> 
>> On May 5, 2009, at 7:56 AM, Morrison, Tom wrote:
>> 
>> > Hi Kumar/Michael...
>> >
>> > Sorry, I really didn't explain myself very well...
>> >
>> > The Problem (answer to Michael):
>> > ================================
>> > We started using a new compiler that upon -O2 optimization - added
>> > heavy SPE related instructions into our applications (where the
older
>> > compiler might not use as many). Once this was done, we started
>> > experiencing problems with data being 'shifted' and/or corrupted
>> > throughout the applications which didn't immediately cause
problems,
>> > but either scribbled on someone else's memory and/or bad results...
>> > We knew where one of the offending scribbles started (by the
shifting
>> > by 1 byte of a structure) and found by comparing binaries with
'older'
>> > compiler vs. this one that the only major difference was the
'density'
>> > of the SPE instructions...
>> >
>> > As to your question, Kumar:
>> > ===========================
>> > Naively, I explicitly enabled the SPE in a BSP 'early_init' program
>> > (as well as enabling Machine Checks) - which is what I meant by
>> > Enabling SPE...
>> 
>> Are you setting MSR_SPE in your own board code?  If so stop doing so.
>> There isn't any need or reason to be doing that.  MSR_SPE will get
set
>> when an application starts using SPE code and the kernel will manage
>> it properly.
>> 
>> - k
>>