From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Andi Kleen <ak@suse.de>
Cc: Randy Dunlap <rdunlap@xenotime.net>,
Linus Torvalds <torvalds@osdl.org>, akpm <akpm@osdl.org>,
Jesper Juhl <jesper.juhl@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH/RFC] Math-emu kills the kernel on Athlon64 X2 II -- it's terminally broken
Date: Tue, 03 Oct 2006 12:53:34 +0100 [thread overview]
Message-ID: <1159876414.17553.29.camel@localhost.localdomain> (raw)
In-Reply-To: <200610031211.46168.ak@suse.de>
Ar Maw, 2006-10-03 am 12:11 +0200, ysgrifennodd Andi Kleen:
> On Tuesday 03 October 2006 05:24, Randy Dunlap wrote:
>
> Actually I looked at the code more closely. It looks like kernel math
> emulation is much more broken. e.g. kernel_fpu_begin() is missing
> code and lots of other paths in i387 that need to check HAVE_HWFP don't.
That check would be wrong anyway. A kernel built with FPU emulation
boots, runs and uses the hardware FPU code correctly. The problem area
is the X86_FEATURE_foo stuff. I think that comes down to a single thing
- if we have FPU disabled clear X86_FEATURE_FXSR|X86_FEATURE_MMX|
X86_FEATURE_SSE* in the boot cpu features during early option
parsing/setup. Basically the emulated FPU is forgetting to tell the
truth about the fact its a very basic FPU.
Alan
next prev parent reply other threads:[~2006-10-03 11:28 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-18 22:18 Math-emu kills the kernel on Athlon64 X2 Jesper Juhl
2006-09-18 22:52 ` Linus Torvalds
2006-09-18 23:14 ` Jesper Juhl
2006-09-18 23:49 ` Linus Torvalds
2006-09-19 0:47 ` Jesper Juhl
2006-09-19 2:18 ` Linus Torvalds
2006-09-18 23:49 ` Sergio Monteiro Basto
2006-09-19 0:02 ` Jesper Juhl
2006-09-19 12:28 ` Krzysztof Halasa
2006-09-20 0:48 ` Sergio Monteiro Basto
2006-09-20 22:31 ` Krzysztof Halasa
2006-09-19 8:01 ` Andi Kleen
2006-09-19 8:31 ` Jesper Juhl
2006-09-19 21:14 ` Jesper Juhl
2006-09-19 22:01 ` Linus Torvalds
2006-09-19 22:16 ` Jesper Juhl
2006-09-19 22:44 ` Jesper Juhl
2006-10-03 2:16 ` [PATCH/RFC] " Randy Dunlap
2006-10-03 2:34 ` Linus Torvalds
2006-10-03 3:24 ` Randy Dunlap
2006-10-03 10:05 ` Andi Kleen
2006-10-03 14:54 ` Linus Torvalds
2006-10-03 10:11 ` [PATCH/RFC] Math-emu kills the kernel on Athlon64 X2 II -- it's terminally broken Andi Kleen
2006-10-03 11:53 ` Alan Cox [this message]
2006-10-03 14:48 ` Linus Torvalds
2006-10-03 4:38 ` [PATCH/RFC] Math-emu kills the kernel on Athlon64 X2 Randy Dunlap
2006-10-03 11:30 ` Alan Cox
2006-10-03 15:10 ` Linus Torvalds
2006-10-03 16:23 ` Randy Dunlap
2006-10-03 16:37 ` Linus Torvalds
2006-10-03 16:49 ` Randy Dunlap
2006-10-03 16:51 ` Linus Torvalds
2006-10-04 19:24 ` Jesper Juhl
2006-10-04 19:43 ` Linus Torvalds
2006-10-04 20:02 ` Jesper Juhl
2006-10-04 22:00 ` Alan Cox
2006-10-04 21:44 ` Andi Kleen
2006-09-20 8:16 ` Andi Kleen
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