linux-kernel - Re: [tip:x86/setup] x86, setup: "glove box" BIOS calls -- infrastructure

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: <49E22A2D.6010009@zytor.com>
Date:	Sun, 12 Apr 2009 10:51:41 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Avi Kivity <avi@...hat.com>, Pavel Machek <pavel@....cz>,
	Ingo Molnar <mingo@...e.hu>, mingo@...hat.com,
	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	hpa@...ux.intel.com, rjw@...k.pl, linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/setup] x86, setup: "glove box" BIOS calls -- infrastructure

Linus Torvalds wrote:
> 
> This discussion is just taking us down a rat-hole of more complexity, and 
> _way_ more fragility.
> 
> I'm absolutely willing to bet that trying to do the BIOS calls will break 
> way more than it will fix. Sure, it will probably work for 99.9% of all 
> BIOSes, but then it will break horribly for some BIOS that tries to do 
> something "clever". SMM has already been mentioned as an example of 
> something that simply isn't virtualizable.
> 
> Timing is another, very traditional, one. There used to be video BIOSes 
> that simply didn't work in a dosbox-like environment because they had 
> tight timing loops that were coupled to hardware. I can pretty much 
> guarantee that that has gone away as far as the video BIOS is concerned, 
> but the main BIOS? Who the hell knows.
> 
> Sure, none of the calls we do to the BIOS from the kernel should need 
> anything fancy at all, and maybe I'm pessimistic. But at the same time, I 
> really don't think the BIOS calls are worth that kind of infrastructure. 
> 
> Sure, go ahead and wrap them in some kind of "save and restore all 
> registers" wrapping, but nothing fancier than that. It would just be 
> overkill, and likely to break more than it fixes.
> 

Agreed completely.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
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/