linux-kernel - Re: [PATCH 2/3] pci: don't assume pref memio are 64bit -v2

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Date:	Sun, 19 Apr 2009 00:09:09 +0400
From:	Ivan Kokshaysky <ink@...assic.park.msu.ru>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Matthew Wilcox <matthew@....cx>, Ingo Molnar <mingo@...e.hu>,
	linux-pci@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] pci: don't assume pref memio are 64bit -v2

On Sat, Apr 18, 2009 at 01:44:51AM -0700, Yinghai Lu wrote:
> and BIOS set
> [    0.240007] pci 0000:00:01.0: bridge 64bit mmio pref: [0xbdf00000-0xddefffff]

An obvious BIOS bug, the bridge base overlaps the physical low RAM
(0x00000000-0xc0000000). Technically speaking, this nonsense *happens*
to work on Intel hardware, so it seems to be quite common bug nowadays -
BIOS writers get lost in ACPI and other "useful" stuff contradicting
the PCI specs.

...

> +	/* don't allocate too high if the pref mem doesn't support 64bit*/
> +	if ((res->flags & (IORESOURCE_PREFETCH | PCI_PREF_RANGE_TYPE_64)) ==
> +	    IORESOURCE_PREFETCH)
> +		max = 0xffffffff;

This effectively destroys non-x86 64-bit arches. You've been told about
that before, so I'm really surprised to see this "patch" once again.

Categorically NACKed.

P.S. I recall that I had a patch that addressed the issue, and Ingo
made some reasonable comments about it. Will post it tomorrow.

Ivan.
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