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Commit dd7c7bc4 authored by Rusty Russell's avatar Rusty Russell
Browse files

virtio: Formally reserve bits 28-31 to be 'transport' features.



We assign feature bits as required, but it makes sense to reserve some
for the particular transport, rather than the particular device.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent faeba830
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+5 −0
Original line number Diff line number Diff line
@@ -113,6 +113,11 @@ static int virtio_dev_probe(struct device *_d)
			set_bit(f, dev->features);
	}

	/* Transport features are always preserved to pass to set_features. */
	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
		if (device_features & (1 << i))
			set_bit(i, dev->features);

	err = drv->probe(dev);
	if (err)
		add_status(dev, VIRTIO_CONFIG_S_FAILED);
+6 −0
Original line number Diff line number Diff line
@@ -18,6 +18,12 @@
/* We've given up on this device. */
#define VIRTIO_CONFIG_S_FAILED		0x80

/* Some virtio feature bits (currently bits 28 through 31) are reserved for the
 * transport being used (eg. virtio_ring), the rest are per-device feature
 * bits. */
#define VIRTIO_TRANSPORT_F_START	28
#define VIRTIO_TRANSPORT_F_END		32

/* Do we get callbacks when the ring is completely used, even if we've
 * suppressed them? */
#define VIRTIO_F_NOTIFY_ON_EMPTY	24