On Mon, Sep 21, 2026 at 09:47:54AM -0600, Mathieu Poirier wrote: > On Wed, Sep 16, 2026 at 11:10:50PM +0200, Francesco Valla wrote: > > There is currently no way to report the VIRTIO_F_VERSION_1 using the > > resource table alone, as the per-vdev feature array is limited to 32 > > bits. > > > > Considering that the VirtIO 1.0 specification is now ~10 years old, > > always report the VIRTIO_F_VERSION_1 feature, as some drivers depend on > > it. > > > > Signed-off-by: Francesco Valla <[email protected]> > > --- > > drivers/remoteproc/remoteproc_virtio.c | 10 ++++++---- > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/remoteproc/remoteproc_virtio.c > > b/drivers/remoteproc/remoteproc_virtio.c > > index 74e0da970f1d..cfd66d9d1c9e 100644 > > --- a/drivers/remoteproc/remoteproc_virtio.c > > +++ b/drivers/remoteproc/remoteproc_virtio.c > > @@ -249,7 +249,7 @@ static u64 rproc_virtio_get_features(struct > > virtio_device *vdev) > > > > rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset; > > > > - return rsc->dfeatures; > > + return rsc->dfeatures | (1ULL << VIRTIO_F_VERSION_1); > > I understand this. > > > } > > > > static void rproc_transport_features(struct virtio_device *vdev) > > @@ -275,14 +275,16 @@ static int rproc_virtio_finalize_features(struct > > virtio_device *vdev) > > /* Give virtio_rproc a chance to accept features. */ > > rproc_transport_features(vdev); > > > > - /* Make sure we don't have any features > 32 bits! */ > > - BUG_ON((u32)vdev->features != vdev->features); > > + /* Make sure we don't have any features > 32 bits except > > VIRTIO_F_VERSION_1 */ > > + if (WARN_ON_ONCE((u32)vdev->features != > > + (vdev->features & ~(1ULL << VIRTIO_F_VERSION_1)))) > > + return -1; > > And this. > > > > > /* > > * Remember the finalized features of our vdev, and provide it > > * to the remote processor once it is powered on. > > */ > > - rsc->gfeatures = vdev->features; > > + rsc->gfeatures = vdev->features & ~(1ULL << VIRTIO_F_VERSION_1); > > > > But I'm having trouble with this one. > > First bit 32 of vdev->features gets cleared and then bit 0 to 31 are assigned > to > rsc->gfeatures. Why bother with clearing bit 32? >
Bits > 31 gets silently dropped because rsc->gfeatures is a u32; this was inserted to explicitly drop the flag that has been inserted before and avoid the "silently". It has no real funtional impact and can be safely dropped. > > return 0; > > } > > > > -- > > 2.55.0 > >
