Messages in this thread | | | Date | Fri, 08 May 2009 08:47:00 +0100 | From | "Jan Beulich" <> | Subject | Re: [Xen-devel] [PATCH 1/9] xen: make sure swiotlb allocation isphysically contigious |
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>>> Jeremy Fitzhardinge <jeremy@goop.org> 08.05.09 02:17 >>> >Impact: make swiotlb allocation suitable for Xen > >When allocating the swiotlb buffer under Xen, make sure the memory is >physically contiguous so that its really suitable for DMA. > >Do this by allocating the memory as usual, but then call a Xen >function to rearrange the underlying pages to be physically >contiguous.
As pointed out before, you must not use alloc_bootmem_low...() here, as on large systems you may otherwise get an allocation failure (i.e. a panic - checking the return value is pointless). The alternative is to fix the bootmem allocator to no longer allocate from bottom up.
Jan
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