From: Prarit Bhargava <prarit@redhat.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
jbarnes@virtuousgeek.org, ed.pollard@ibm.com,
epollard@redhat.com
Subject: Re: [PATCH]: PCI: GART iommu alignment fixes [v2]
Date: Thu, 24 Jul 2008 08:49:54 -0400 [thread overview]
Message-ID: <48887A72.1070209@redhat.com> (raw)
In-Reply-To: <20080724123755.GP31439@8bytes.org>
> But I think Prarit is right with this change. If the interface defines
> this behavior the IOMMU drivers have to implement it. I am just
> wondering that the problem never showed up before. The GART driver is a
> few years old now.
>
>
Joerg -- there's an easy explanation for this. This will only happen
when a 32-bit device requests DMA memory and all memory below 4G is
used. Just doing a quick overview of a few systems, allocated DMA
memory is usually less than 512M of the system memory so it is unlikely
a system hits the 4G limit.
In addition to that most systems do not reserve all or most of the lower
4G in the e820 maps. Those that do are usually larger systems.
ie) The only reason we're seeing this now is because large memory
footprint systems are coming online -- IMO ;)
P.
next prev parent reply other threads:[~2008-07-24 12:50 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-23 11:19 [PATCH]: PCI: GART iommu alignment fixes [v2] Prarit Bhargava
2008-07-23 22:10 ` Joerg Roedel
2008-07-23 23:14 ` FUJITA Tomonori
2008-07-23 23:47 ` Prarit Bhargava
2008-07-24 7:46 ` Joerg Roedel
2008-07-24 10:09 ` Prarit Bhargava
2008-07-24 10:34 ` FUJITA Tomonori
2008-07-24 12:37 ` Joerg Roedel
2008-07-24 12:49 ` Prarit Bhargava [this message]
2008-07-24 13:32 ` FUJITA Tomonori
2008-07-24 14:31 ` Prarit Bhargava
2008-07-24 14:40 ` FUJITA Tomonori
2008-07-24 15:13 ` Prarit Bhargava
2008-07-24 14:45 ` Prarit Bhargava
2008-07-28 22:23 ` Jesse Barnes
2008-07-29 14:24 ` Prarit Bhargava
2008-07-29 17:08 ` Jesse Barnes
2008-07-30 0:43 ` FUJITA Tomonori
2008-08-06 12:29 ` Prarit Bhargava
2008-08-06 13:23 ` Prarit Bhargava
2008-08-06 13:35 ` FUJITA Tomonori
2008-08-06 14:32 ` Prarit Bhargava
2008-08-07 17:03 ` Jesse Barnes
2008-08-07 17:41 ` Prarit Bhargava
2008-08-08 7:12 ` Muli Ben-Yehuda
2008-08-08 15:18 ` Prarit Bhargava
2008-08-08 16:15 ` Jesse Barnes
2008-08-08 21:13 ` FUJITA Tomonori
2008-08-09 1:40 ` Prarit Bhargava
2008-08-09 3:50 ` FUJITA Tomonori
2008-08-15 16:16 ` Ingo Molnar
2008-08-15 18:00 ` Ingo Molnar
2008-08-15 20:39 ` Prarit Bhargava
2008-08-15 21:20 ` Ingo Molnar
2008-08-16 1:15 ` FUJITA Tomonori
2008-08-17 12:56 ` Ingo Molnar
2008-08-17 15:36 ` FUJITA Tomonori
2008-08-17 15:42 ` Ingo Molnar
2008-08-17 15:48 ` FUJITA Tomonori
2008-08-17 15:54 ` FUJITA Tomonori
2008-08-07 17:45 ` Prarit Bhargava
2008-07-23 23:23 ` FUJITA Tomonori
2008-07-23 23:24 ` Prarit Bhargava
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