Re: [PATCH v4 11/42] virtio: add legacy feature table support
From: Cornelia Huck <hidden>
Date: 2014-11-25 17:53:50
Also in:
lkml
On Tue, 25 Nov 2014 18:42:09 +0200 "Michael S. Tsirkin" [off-list ref] wrote:
virtio blk has some legacy feature bits that modern drivers
virtio-blk
must not negotiate, but are needed for old legacy hosts (e.g. that dn't support virtio scsi).
(that e.g. don't support virtio-scsi)
Allow a separate legacy feature table for such cases. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- include/linux/virtio.h | 4 ++++ drivers/virtio/virtio.c | 25 ++++++++++++++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-)
quoted hunk ↗ jump to hunk
@@ -177,7 +185,22 @@ static int virtio_dev_probe(struct device *_d) driver_features |= (1ULL << f); } - dev->features = driver_features & device_features; + /* Some drivers have a separate feature tables for virtio v1.0 */
/* some drivers have a separate feature table for legacy virtio */ ?
+ if (drv->feature_table_legacy) {
+ driver_features_legacy = 0;
+ for (i = 0; i < drv->feature_table_size_legacy; i++) {
+ unsigned int f = drv->feature_table_legacy[i];
+ BUG_ON(f >= 64);
+ driver_features_legacy |= (1ULL << f);
+ }
+ } else {
+ driver_features_legacy = driver_features;
+ }(...)