virtio: use u32, not bitmap for features

It seemed like a good idea to use bitmap for features
in struct virtio_device, but it's actually a pain,
and seems to become even more painful when we get more
than 32 feature bits.  Just change it to a u32 for now.

Based on patch by Rusty.

Suggested-by: David Hildenbrand <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
Signed-off-by: Cornelia Huck <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: Cornelia Huck <[email protected]>
This commit is contained in:
Michael S. Tsirkin 2014-10-07 16:39:42 +02:00
commit e16e12be34
16 changed files with 42 additions and 74 deletions

View file

@ -137,14 +137,14 @@ static void lg_finalize_features(struct virtio_device *vdev)
vring_transport_features(vdev);
/*
* The vdev->feature array is a Linux bitmask: this isn't the same as a
* the simple array of bits used by lguest devices for features. So we
* do this slow, manual conversion which is completely general.
* Since lguest is currently x86-only, we're little-endian. That
* means we could just memcpy. But it's not time critical, and in
* case someone copies this code, we do it the slow, obvious way.
*/
memset(out_features, 0, desc->feature_len);
bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
for (i = 0; i < bits; i++) {
if (test_bit(i, vdev->features))
if (__virtio_test_bit(vdev, i))
out_features[i / 8] |= (1 << (i % 8));
}