Re: Freeze on FPU exception with Athlon

[torvalds@transmeta.com (Linus Torvalds)]

In article <20001118014019.18006.qmail@web3404.mail.yahoo.com>,
=?iso-8859-1?q?Markus=20Schoder?=  <markus_schoder@yahoo.de> wrote:
>The following small program (linked against glibc 2.1.3) reliably
>freezes my system (Athlon Thunderbird CPU) with at least kernels
>2.4.0-test10 and 2.4.0-test11-pre5.  Even the SysRq keys do not work
>after the freeze.

Are you sure sysrq doesn't work? Many distributions will disable the
kernel printing to the console, or move it to console 7 or similar. 

It would be really good to get the EIP trace of RightAlt+ScrollLock
pressed a few times if you can try to see if you can use klogd to enable
proper printk's.

>Older kernels (e.g. 2.3.40) seem to work.  Any Ideas?

The FP exception handling has certainly changed, but the changes should
all have affected mainly just PIII kernels with XMM support enabled. An
Athlon system should have been pretty unaffected. But I'll take a look
if I see something obvious.

One thing to try: if interrupts really don't work for you (and if SysRq
doesn't work, that may be the case), please test out a kernel that
simply ignores irq13 by just commenting out the line

	setup_irq(13, &irq13);

in arch/i386/kernel/i8259.c.  Does that make any difference? (irq13
shouldn't be used any more, it's horrible legacy crap, but we do want to
support even horrible legacy systems). 

		Linus
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