linux-kernel - Re: Math-emu kills the kernel on Athlon64 X2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.64.0609181549200.4388@g5.osdl.org>
Date:	Mon, 18 Sep 2006 15:52:14 -0700 (PDT)
From:	Linus Torvalds <torvalds@...l.org>
To:	Jesper Juhl <jesper.juhl@...il.com>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	billm@...bpc.org.au, billm@...urbia.net
Subject: Re: Math-emu kills the kernel on Athlon64 X2



On Tue, 19 Sep 2006, Jesper Juhl wrote:
> 
> If I enable the math emulator in 2.6.18-rc7-git2 (only version I've
> tried this with) and then boot the kernel with "no387" then I only get
> as far as lilo's "...Booting the kernel." message and then the system
> hangs.

I'm wondering if it tries to use the MMX/XMM stuff for memcpy and friends. 

I'm also wondering why you'd be doing what you seem to try to be doing in 
the first place ;)

Basically, "no387" doesn't seem to disable any of the fancier FPU 
features, even though it obviously should. If you ask for math emulation, 
you'll get emulation faults for _all_ of the modern MMX stuff too (which 
we don't do). 

It's entirely possible that nobody has ever tested this combination.

		Linus
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/