From: Cornelia Huck Subject: Re: [PATCH v4 11/42] virtio: add legacy feature table support Date: Tue, 25 Nov 2014 18:53:42 +0100 Message-ID: <20141125185342.761bf72e.cornelia.huck@de.ibm.com> References: <1416933600-21398-1-git-send-email-mst@redhat.com> <1416933600-21398-12-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1416933600-21398-12-git-send-email-mst@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Michael S. Tsirkin" Cc: Pawel Moll , rusty@au1.ibm.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, pbonzini@redhat.com, David Miller List-Id: virtualization@lists.linuxfoundation.org On Tue, 25 Nov 2014 18:42:09 +0200 "Michael S. Tsirkin" 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 > --- > include/linux/virtio.h | 4 ++++ > drivers/virtio/virtio.c | 25 ++++++++++++++++++++++++- > 2 files changed, 28 insertions(+), 1 deletion(-) > > @@ -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; > + } (...)