Messages in this thread | | | Subject | Re: [RFC] block layer support for DMA IOMMU bypass mode | From | James Bottomley <> | Date | 01 Jul 2003 12:28:47 -0500 |
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On Tue, 2003-07-01 at 12:09, Andi Kleen wrote: > I assume on 2.5 has this problem, not 2.4, right?
Yes, sorry, I'm so focussed on 2.5 I keep forgetting 2.4.
> But a mask is not good for AMD64 because there is no guarantee > that the bypass/iommu address is checkable using a mask > (K8 uses an memory hole for IOMMU purposes and for various > reasons the hole can be anywhere in the address space) > > This means x86_64 needs an function. Also the name is quite weird and > the issue is not really BIO specific. How about just calling it > iommu_address() ?
The name was simply to be consistent with BIO_VMERGE_BOUNDARY which is another asm/io.h setting for this.
Could you elaborate more on the amd64 IOMMU window. Is this a window where IOMMU mapping always takes place?
I'm a bit reluctant to put a function like this in because the block layer does a very good job of being separate from the dma layer. Maintaining this separation is one of the reasons I added a dma_mask to the request_queue, not a generic device pointer.
James
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