linux-kernel - Re: pci-disable-decode-of-io-memory-during-bar-sizing.patch

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: <200710301531.58957.jbarnes@virtuousgeek.org>
Date:	Tue, 30 Oct 2007 15:31:57 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Robert Hancock <hancockr@...w.ca>, Greg KH <greg@...ah.com>,
	akpm@...ux-foundation.org, ak@...e.de, rajesh.shah@...el.com,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: pci-disable-decode-of-io-memory-during-bar-sizing.patch

On Tuesday, October 30, 2007 3:22 pm Linus Torvalds wrote:
> On Tue, 30 Oct 2007, Jesse Barnes wrote:
> > The per-device flag is fine with me, but I should make something
> > clear:
> >
> > MMCONFIG IS NOT BROKEN!
>
> Trust me, it is.
>
> The particular problem _you_ had with it is only a small small part
> of the bugs we have had.
>
> > What's broken is our PCI probing with certain address space layouts
> > that include MMCONFIG space.
>
> No. You really don't see the big picture. There's been tons of
> problems with MMCONFIG. Like the fact that other devices have their
> IO regions registered on top of it, because the MMCONFIG thing was
> done as a hidden resource. Or the fact that the area claimed was too
> small. Or too large. Or not listed at all.

Yeah, that's definitely a problem, and would be a firmware bug.  There's 
no doubt that firmwares have had trouble with this in the past, but 
given that Vista now relies on this stuff working, it's a lot more 
likely to be reliable in current and future systems.

> The whole thing is a total disaster. I told Intel engineers literally
> *years* ago to not do that idiotic "hidden IO resources that are
> described by firmware that then inevitably gets things wrong", and
> yet what happens? Every single time.

I don't disagree there.  I'm just saying the actual mechanism is fine 
(as illustrated by the numerous non-PC ports of Linux), and this 
particular problem, at least, isn't really specific to how MMCONFIG is 
described or configured by the firmware and OS, it's simply a Linux 
problem.

But like I said, the per-device flag Arjan suggested is fine with me...

Jesse
-
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/