On Tue, 05 Feb 2008 20:41:38 -0800 (PST) David Miller <[EMAIL PROTECTED]> wrote:
> > The sparc64 change: > > commit fde6a3c82d67f592eb587be4d12222b0ae6d4321 > Author: FUJITA Tomonori <[EMAIL PROTECTED]> > Date: Mon Feb 4 22:28:02 2008 -0800 > > iommu sg merging: sparc64: make iommu respect the segment size limits > > This patch makes iommu respect segment size limits when merging sg > lists. > > Signed-off-by: FUJITA Tomonori <[EMAIL PROTECTED]> > Cc: Jeff Garzik <[EMAIL PROTECTED]> > Cc: James Bottomley <[EMAIL PROTECTED]> > Acked-by: Jens Axboe <[EMAIL PROTECTED]> > Cc: "David S. Miller" <[EMAIL PROTECTED]> > Signed-off-by: Andrew Morton <[EMAIL PROTECTED]> > Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]> > > has significant errors and is going to eat people's disks, as it just > nearly did to mine. Really sorry about it. > Typically what you'll see are NULL pointer derefernces in > dma_4v_map_sg() and dma_4u_map_sg() and then the kernel usually craps > on your superblock very shortly thereafter. > > The changeset above modified only prepare_sg() but that is only the > first pass of the SG mapping algorithm of the sparc64 IOMMU layer. > > The second pass that fills in the entries depends upon how the first > pass does things. So if you change the first pass decision making you > have to update the second pass's as well. > > That second pass is implemented in fill_sg() (there is a version in > both arch/sparc64/kernel/iommu.c and arch/sparc64/kernel/pci_sun4v.c), > which probably needs new logic as was added to prepare_sg() to handle > dma_get_max_seg_size(). PARISC, Alpha, and IA64 IOMMUs use the two-pass algorithm like SPARC but their first pass decides how to merge sg entires (and stores that information in the sg entries), then the second pass simpliy follows it (Hopefully I understand these IOMMUs correctly, or else I break them too). I'll try this work again for 2.6.26. The SPARC IOMMUs are the most complicated and seems that few people tests the -mm SPARC code. So I guess that I need to find a SPARC box... Thanks, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
