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

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Message-ID: <20100426133757.3e1d0a75@virtuousgeek.org>
Date:	Mon, 26 Apr 2010 13:37:57 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Bjorn Helgaas <bjorn.helgaas@...com>
Cc:	Andy Isaacson <adi@...apodia.org>,
	"R. Andrew Bailey" <bailey@...mai.com>,
	Yinghai <yinghai.lu@...cle.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, guenter.roeck@...csson.com,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"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 Mon, 26 Apr 2010 14:27:56 -0600
Bjorn Helgaas <bjorn.helgaas@...com> wrote:
> I'm a little concerned that those patches are a sledgehammer approach.
> Previously, IORESOURCE_BUSY has basically been used for mutual exclusion
> between drivers that would otherwise claim the same resource.  It hasn't
> been used to guide resource assignment in the PCI/PNP/etc core.  Maybe
> it's a good idea to also use IORESOURCE_BUSY there, but I'm not sure.
> Right now it feels like undesirable overloading to me.

I guess that's true, removing those regions from the pool entirely
might be better?  Or some other, clear way of expressing that the
regions aren't available to drivers.  Maybe we need a new IO resource
type for platform ranges.

> I think it also leads to at least one problem: Guenter's machine has no
> VGA but has a PCI device that lives at 0xa0000.  The driver for that
> device won't be able to request that region if the arch code has marked
> it busy.

Ah good point, so we'll want another approach at any rate.  Yinghai?

-- 
Jesse Barnes, Intel Open Source Technology Center
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