Il 26/04/2012 15:49, Christian Borntraeger ha scritto: > Currently the sector value for the geometry is masked based on > the sector size. This works fine for with 512 physical sector size, > but it fails for dasd devices on s390. A dasd device can have > a physical block size of 4096 (== same for logical block size) > and a typcial geometry of 15 heads and 12 sectors per cyl. > The ibm partition detection relies on a correct geometry > reported by the device. Unfortunately the current code changes > 12 to 8. (This would be necessary for a physical block size / > device size that is not dividable by 4096) but for dasd this > is not the case. > > This tries to fix the block layer by handling both cases > dasd and non-dasd by taking the physical block size into > account. > > Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com> > CC: Christoph Hellwig <h...@lst.de> > --- > hw/virtio-blk.c | 12 +++++++++++- > 1 files changed, 11 insertions(+), 1 deletions(-) > > diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c > index 49990f8..5258533 100644 > --- a/hw/virtio-blk.c > +++ b/hw/virtio-blk.c > @@ -483,6 +483,7 @@ static void virtio_blk_update_config(VirtIODevice *vdev, > uint8_t *config) > uint64_t capacity; > int cylinders, heads, secs; > int blk_size = s->conf->logical_block_size; > + int pblk_size = s->conf->physical_block_size; > > bdrv_get_geometry(s->bs, &capacity); > bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs); > @@ -494,7 +495,16 @@ static void virtio_blk_update_config(VirtIODevice *vdev, > uint8_t *config) > stw_raw(&blkcfg.min_io_size, s->conf->min_io_size / blk_size); > stw_raw(&blkcfg.opt_io_size, s->conf->opt_io_size / blk_size); > blkcfg.heads = heads; > - blkcfg.sectors = secs & ~s->sector_mask; > + /* > + * we must round down the block device size to a multiple of the logical > + * block size. The geometry value for sectors is based on the physical > + * sector size and NOT on the Linux default block size of 512. For > + * example a dasd device usually has 12 sectors per track and each > + * sector has 4096 bytes (the whole cylinder == 48k). The geometry > + * is specified as secs=12. Thus we cannot use sector_mask, instead > + * we have to use some special case. > + */ > + blkcfg.sectors = secs & ~(blk_size / pblk_size - 1);
I'm not sure here what you mean. Usually blk_size >= pblk_size on non-s390 systems, so this is completely different from the previous code, which is effectively blkcfg.sectors = secs & ~(blk_size / 512 - 1); I wonder if s390 gives a different meaning to logical vs. physical sector sizes, compared to what virtio expects (which is what SCSI says, basically). Physical block sizes on non-s390 systems are really just useful as an alignment hint, they do not affect correctness. Paolo > blkcfg.size_max = 0; > blkcfg.physical_block_exp = get_physical_block_exp(s->conf); > blkcfg.alignment_offset = 0;
