On Mon, Apr 30, 2012 at 4:52 PM, Michael Tokarev <m...@tls.msk.ru> wrote: > This value is used currently for virtio-blk only. It was defined > as uint16_t before, which is the same as in kernel<=>user interface > (in virtio_blk.h, struct virtio_blk_config). But the problem is > that in kernel<=>user interface the units are sectors (which is > usually 512 bytes or more), while in qemu it is in bytes. However, > for, say, md raid5 arrays, it is typical to have actual min_io_size > of a host device to be large. For example, for raid5 device of > 3 drives with 64Kb chunk size, that value will be 128Kb, which does > not fit in a uint16_t anymore. > > Increase the value size from 16bits to 32bits for now. > > But apparently, the kernel<=>user interface needs to be fixed too > (while it is much more difficult due to compatibility issues), > because even with 512byte units, the 16bit value there will overflow > too with quite normal MD RAID configuration. > > Signed-off-by: Michael Tokarev <m...@tls.msk.ru> > --- > block.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-)
Which kernel<=>user interface? Reviewed-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
