From: Christoph Hellwig <h...@lst.de> IDE is a bit ugly in this respect. For one it doesn't really keep track of a sector size - most of the protocol is in units of 512 bytes, and we assume 2048 bytes for CDROMs which is correct most of the time.
Second IDE allocates an I/O buffer long before we know if we're dealing with a CDROM or not, so increase the alignment for the io_buffer unconditionally. Signed-off-by: Christoph Hellwig <h...@lst.de> Signed-off-by: Kevin Wolf <kw...@redhat.com> --- hw/ide/core.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/hw/ide/core.c b/hw/ide/core.c index 1e466d1..06b6e14 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -2645,6 +2645,7 @@ int ide_init_drive(IDEState *s, BlockDriverState *bs, if (bdrv_get_type_hint(bs) == BDRV_TYPE_CDROM) { s->drive_kind = IDE_CD; bdrv_set_change_cb(bs, cdrom_change_cb, s); + bs->buffer_alignment = 2048; } else { if (!bdrv_is_inserted(s->bs)) { error_report("Device needs media, but drive is empty"); @@ -2679,7 +2680,8 @@ static void ide_init1(IDEBus *bus, int unit) s->bus = bus; s->unit = unit; s->drive_serial = drive_serial++; - s->io_buffer = qemu_blockalign(s->bs, IDE_DMA_BUF_SECTORS*512 + 4); + /* we need at least 2k alignment for accessing CDROMs using O_DIRECT */ + s->io_buffer = qemu_memalign(2048, IDE_DMA_BUF_SECTORS*512 + 4); s->io_buffer_total_len = IDE_DMA_BUF_SECTORS*512 + 4; s->smart_selftest_data = qemu_blockalign(s->bs, 512); s->sector_write_timer = qemu_new_timer(vm_clock, -- 1.7.2.2