On Sun, 2012-10-21 at 16:25 +0200, Ingo wrote: > Am 21.10.2012 14:20, schrieb Per Foreby: > > > Note that this is 1023 memory banks, not 1024, so it's not exactly 64 MB > > (65536 kB). Maybe the reason why it almost works with 256 MB is that the > > kernel always thinks that we have exactly 256 MB but the Mobo supplies > > one memory bank less. Just a theory.. > > Per, me came another idea. Some postings up Ben Hutching stated: > > "The driver calls ioremap_wc() which will enable write-combining through > the PAT in recent processors." > > Isn't this "address translation" how I/O remapping (IOMMU) also called > VT-d works? [...] PAT is a feature of the ordinary MMU, not an IOMMU. (The last I heard, Intel's integrated GPUs were totally incompatible with VT-d (partly because they are not normal PCIe devices). Linux therefore doesn't allow them to be in a VT-d remapping domain.) Ben. -- Ben Hutchings Humour is the best antidote to reality.
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