On 07/09/2016 09:31, Mark Cave-Ayland wrote: > Now that the 2.8 tree is open, I'd like to resurrect this earlier patch > to switch the macio controller over to the new byte-aligned DMA helpers: > https://lists.gnu.org/archive/html/qemu-devel/2016-05/msg04907.html. > > The first patch in the series is a hack to work around the issue that > byte-aligned qiovs are being truncated with the existing code. git blame > shows that this code was introduced by this commit: > > > commit 58f423fbd5f7f435e8dc56dfa565b043d20d1e1b > Author: Kevin Wolf <kw...@redhat.com> > Date: Wed Jul 9 19:17:30 2014 +0200 > > dma-helpers: Fix too long qiov > > If the size of the scatter/gather list isn't a multiple of 512, the > number of sectors for the block layer request is rounded down, resulting > in a qiov that doesn't match the request length. Truncate the qiov > to the > new length of the request. > > This fixes the IDE qtest case /x86_64/ide/bmdma/short_prdt. > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > Reviewed-by: Eric Blake <ebl...@redhat.com> > > > Kevin/Paolo - what should be the correct behaviour here given that the > underlying APIs are now byte-aligned?
I think the expected alignment should be passed down to dma-helpers, and they should ignore the unaligned tail of the QEMUSGList. Paolo
