From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Pavel Machek <pavel@suse.cz>
Cc: kernel list <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@elte.hu>, Dave Jones <davej@codemonkey.org.uk>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: pci-gart_64.c: could we get better explanation?
Date: Tue, 27 May 2008 05:51:39 +1000 [thread overview]
Message-ID: <1211831499.3286.2.camel@pasglop> (raw)
In-Reply-To: <20080526184703.GA17369@elf.ucw.cz>
On Mon, 2008-05-26 at 20:47 +0200, Pavel Machek wrote:
> Hi!
>
> +++ b/arch/x86/kernel/pci-gart_64.c
> @@ -774,6 +778,7 @@ #endif
>
> /*
> * Try to workaround a bug (thanks to BenH)
> * Set unmapped entries to a scratch page instead of 0.
> * Any prefetches that hit unmapped entries won't get an bus abort
>
> Could someone explain? Which bug is being worked around? CPUs
> prefetching over NULL?
P2P bridge prefetching on DMA reads.
Ben.
next prev parent reply other threads:[~2008-05-26 19:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-26 18:47 pci-gart_64.c: could we get better explanation? Pavel Machek
2008-05-26 19:51 ` Benjamin Herrenschmidt [this message]
2008-06-25 22:25 ` Pavel Machek
2008-06-26 13:17 ` Ingo Molnar
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