Messages in this thread | | | Date | Thu, 24 May 2007 10:57:19 +0100 | From | Alan Cox <> | Subject | Re: Define CONFIG_BOUNCE to avoid useless inclusion of bounce buffer logic. |
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> Also there is the problem that some drivers use ZONE_DMA allocations > because their device can only generate addresses below some limit, but > on a platform with an IOMMU there is in fact no restriction on what > memory the device can access.
Bzzzzzt - have to call your bluff on that one
The IOMMU mapping window itself may be out of range of some devices. This is a big problem on AMD64 where the GART window is above the 2GB boundary - you can do 64->32 nicely but 32->31/30/28/24, all of which turn up on PC hardware, are no solved by the IOMMU only by GFP_DMA
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