Finalized FPU Crash Fix?
Hello everybody,
Is there a general concensus that the one-liner in 2.6.7 is an appropriate fix for the FPU hang/crash bug? I have several machines running 2.4.x which require that outside people have shell access. Needless to say, I'm somewhat nervous about this problem =)
I'm trying to find a nice balance between potential downtime due to malicious users and loss of functionality/b0rkedness due to unforeseen bugs in quick fixes. I've seen at least three different solutions to this problem; two of them have confirmed negative side-effects. Noone seems to have complained about the one-liner. Does anyone foresee problems here, or should this be the correct fix (it seems right to me, but my CPU-level voodoo is weak).
Thanks in advance,
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/jbm, but you can call me Josh. Really, you can. "People shouldn't see man-made global disasters as a bad thing, they should see them as scientific breakthroughs waiting to happen." -- The Onion
Re: Finalized FPU Crash Fix? [2.2.x]
Quoted 6 lines · Josh Myer
Hello everybody,
Is there a general concensus that the one-liner in 2.6.7 is an appropriate fix for the FPU hang/crash bug? I have several machines running 2.4.x which require that outside people have shell access. Needless to say, I'm somewhat nervous about this problem =)
And how this look in 2.2.x kernels? One guy here tells me that after running
http://linuxreviews.org/news/2004-06-11_kernel_crash/index.html#toc1the 2.2 kernel freezes.
Is such fix right one? 2.2.x doesn't crash with it.
Index: SOURCES/kernel-fwait-2.2.patch
kernel-fwait-2.2.patch Thu Jun 17 15:34:36 2004 renamed from dev/null Thu Jun 17 15:34:42 2004 +10 -0
@@ -0,0 +1,10 @@ +--- linux-2.2.26/include/asm-i386/processor.h~ Thu Jun 17 17:19:57 2004 ++++ linux-2.2.26/include/asm-i386/processor.h Thu Jun 17 17:32:36 2004 +@@ -426,6 +426,7 @@ + + #define clear_fpu(tsk) do { \ + if (tsk->flags & PF_USEDFPU) { \ ++ asm volatile("fnclex ; fwait"); \ + tsk->flags &= ~PF_USEDFPU; \ + stts(); \ + } \
Signature · 2 lines
Arkadiusz Miśkiewicz CS at FoE, Wroclaw University of Technology arekm.pld-linux.org, 1024/3DB19BBD, JID: arekm.jabber.org, PLD/Linux