linux-kernel - Re: [PATCH] x86/PCI: never allocate PCI MMIO resources below BIOS

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Message-Id: <201004270911.12124.bjorn.helgaas@hp.com>
Date:	Tue, 27 Apr 2010 09:11:10 -0600
From:	Bjorn Helgaas <bjorn.helgaas@...com>
To:	Yinghai <yinghai.lu@...cle.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Isaacson <adi@...apodia.org>,
	"R. Andrew Bailey" <bailey@...mai.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, guenter.roeck@...csson.com,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Renninger <trenn@...e.de>, yaneti@...lera.com
Subject: Re: [PATCH] x86/PCI: never allocate PCI MMIO resources below    BIOS_END

On Monday 26 April 2010 07:41:55 pm Yinghai wrote:
> On 04/26/2010 06:27 PM, Linus Torvalds wrote:
> > Do we actually have a regression left with Bjorn's patch?

After the pcibios_align_resource() patch, I'm not aware of any regressions.

But let's double-check this:

> also find one AMD system:
> [    7.056011] pci_root PNP0A03:00: host bridge window [mem 0xfed20000-0xffffffff]
> ...
> pci assign unassign code could use range like [mem 0xfed20000-0xffffffff] wrongly.

I agree, it's very unlikely that it's safe to put PCI devices all the
way up to 0xffffffff.  I suspect this might be fixed by d558b483d5a,
which computes the end of the bridge window using _MAX rather than _LEN.

See https://bugzilla.kernel.org/show_bug.cgi?id=15480#c15 for an example
similar to the one above: we originally thought the window was
[mem 0xcff00000-0xffffffff], but d558b483d5a changes that to
[mem 0xcff00000-0xfebfffff], which matches what Windows found.

Yinghai, can you take a look at your AMD system again with a kernel that
includes d558b483d5a, and see whether we still have a problem?  If we
*do* still have a problem, please open a bugzilla and attach a dmesg log
with ACPI resource info collected with the debug patch here:
https://bugzilla.kernel.org/show_bug.cgi?id=15533#c5

Bjorn
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