tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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: Rusty Russell <rusty@rustcorp.com.au>
+11
+5
drivers/virtio/virtio.c
+5
drivers/virtio/virtio.c
···
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set_bit(f, dev->features);
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}
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+
/* Transport features are always preserved to pass to set_features. */
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+
for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
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+
if (device_features & (1 << i))
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+
set_bit(i, dev->features);
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+
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err = drv->probe(dev);
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if (err)
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add_status(dev, VIRTIO_CONFIG_S_FAILED);
+6
include/linux/virtio_config.h
+6
include/linux/virtio_config.h
···
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18
/* We've given up on this device. */
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#define VIRTIO_CONFIG_S_FAILED 0x80
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+
/* Some virtio feature bits (currently bits 28 through 31) are reserved for the
22
+
* transport being used (eg. virtio_ring), the rest are per-device feature
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+
* bits. */
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+
#define VIRTIO_TRANSPORT_F_START 28
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+
#define VIRTIO_TRANSPORT_F_END 32
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+
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/* Do we get callbacks when the ring is completely used, even if we've
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* suppressed them? */
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#define VIRTIO_F_NOTIFY_ON_EMPTY 24