Re: i387/FPU init issues...

From: Ingo Molnar
Date: Sat May 03 2008 - 15:55:24 EST



* H. Peter Anvin <hpa@xxxxxxxxx> wrote:

>> This might also be caused by a calibration error. We've seen enough
>> of them already.
>
> No doubt. However, there is *something* ugly going on.

i think a vital clue can be found in the original report:

| I am able to reproduce the issue consistently on my laptop using qemu
| (which helped speed debugging a bit). I have also narrowed it down to
| include/asm-x86/i387.h::__save_init_fpu in (32 bit version) - it dies
| somewhere in calling the following line:

so it might just be incorrect Qemu emulation of a PII's NOP instruction?

(which btw. probably proves that Linux is the first OS to make
intelligent use of those instructions?)

Ingo
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