From: Andi Kleen <ak@suse.de>
To: Ashok Raj <ashok.raj@intel.com>
Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, gregkh@suse.de,
muli@il.ibm.com, asit.k.mallick@intel.com,
suresh.b.siddha@intel.com, anil.s.keshavamurthy@intel.com,
arjan@linux.intel.com, shaohua.li@intel.com
Subject: Re: [Intel IOMMU][patch 4/8] Supporting Zero Length Reads in Intel IOMMU.
Date: Tue, 24 Apr 2007 21:28:11 +0200 [thread overview]
Message-ID: <200704242128.12057.ak@suse.de> (raw)
In-Reply-To: <20070424061037.821838000@intel.com>
On Tuesday 24 April 2007 08:03:03 Ashok Raj wrote:
> PCI specs permit zero length reads (ZLR) even if the mapping for that region
> is write only. Support for this feature is indicated by the presence of a bit
> in the DMAR capability. If a particular DMAR does not support this capability
> we map write-only regions as read-write.
>
> This option can also provides a workaround for some drivers that request
> a write-only mapping when they really should request a read-write.
> (We ran into one such case in eepro100.c in handling rx_ring_dma)
Better just fix the drivers instead of adding such hacks
-Andi
next prev parent reply other threads:[~2007-04-24 19:30 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-24 6:02 [Intel IOMMU][patch 0/8] Intel IOMMU Support Ashok Raj
2007-04-24 6:03 ` [Intel IOMMU][patch 1/8] ACPI support for Intel Virtualization Technology for Directed I/O Ashok Raj
2007-04-24 18:50 ` Andi Kleen
2007-04-24 20:17 ` Ashok Raj
2007-04-24 6:03 ` [Intel IOMMU][patch 2/8] Some generic search functions required to lookup device relationships Ashok Raj
2007-04-24 6:03 ` [Intel IOMMU][patch 3/8] Generic hardware support for Intel IOMMU Ashok Raj
2007-04-24 19:27 ` Andi Kleen
2007-04-24 20:59 ` Ashok Raj
2007-04-25 1:17 ` Shaohua Li
2007-04-25 6:53 ` Andi Kleen
2007-04-24 6:03 ` [Intel IOMMU][patch 4/8] Supporting Zero Length Reads in " Ashok Raj
2007-04-24 19:28 ` Andi Kleen [this message]
2007-04-24 20:42 ` Ashok Raj
2007-04-24 21:00 ` David Miller
2007-04-24 6:03 ` [Intel IOMMU][patch 5/8] Graphics driver workarounds to provide unity map Ashok Raj
2007-04-24 6:03 ` [Intel IOMMU][patch 6/8] Doc updates for Intel Virtualization Technology for Directed I/O Ashok Raj
2007-04-24 6:03 ` [Intel IOMMU][patch 7/8] Support for legacy ISA devices Ashok Raj
2007-04-24 19:31 ` Andi Kleen
2007-04-24 20:33 ` Arjan van de Ven
2007-04-24 20:39 ` Ashok Raj
2007-04-24 6:03 ` [Intel IOMMU][patch 8/8] Preserve some Virtual Address when devices cannot address entire range Ashok Raj
2007-04-24 19:33 ` Andi Kleen
2007-04-24 20:33 ` Ashok Raj
2007-04-24 21:12 ` Andi Kleen
2007-04-24 21:23 ` David Miller
2007-04-24 21:32 ` Roland Dreier
2007-04-24 21:47 ` David Miller
2007-04-24 21:38 ` Ashok Raj
2007-04-24 21:50 ` David Miller
2007-04-24 22:03 ` Andi Kleen
2007-04-24 22:26 ` Ashok Raj
2007-04-25 1:12 ` H. Peter Anvin
2007-04-25 6:55 ` Andi Kleen
2007-04-24 23:22 ` Alan Cox
-- strict thread matches above, loose matches on Subject: below --
2007-04-23 16:38 [Intel IOMMU][patch 0/8] Intel IOMMU Support Ashok Raj
2007-04-23 16:38 ` [Intel IOMMU][patch 4/8] Supporting Zero Length Reads in Intel IOMMU Ashok Raj
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