On Thu, Oct 01, 2015 at 02:15:45PM +1000, Michael Ellerman wrote: >On Thu, 2015-10-01 at 07:50 +0800, Wei Yang wrote: >> Hmm... some comments on this one? like it or not? > >It sounds like it's fixing a bug, but you don't really say. Have you seen this >fail in the wild?
Hmm... as described in the commit log, this would be a bug when PAGE_SIZE is much smaller than IOMMU Page Size. This configuration doesn't happen on current platform. So I didn't see this failure yet. > >Which commit introduced the breakage? Hmm... maybe we could say it is 'commit d084775738b7 <powerpc/iommu: Update the generic code to use dynamic iommu page sizes>'. From this commit, powerpc iommu supports dynamic iommu page size. Before this commit, the size is aligned with PAGE_SIZE, so the value after shift would be non-zero. After this commit, when PAGE_SIZE is smaller than the IOMMU Page Size, shift right will make the size 0. > >cheers > -- Richard Yang Help you, Help me _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev