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virtio: meet virtio spec by finalizing features before using device 

Virtio devices are supposed to negotiate features before they start using
the device, but the current code doesn't do this.  This is because the
driver's probe() function invariably has to add buffers to a virtqueue,
or probe the disk (virtio_blk).

This currently doesn't matter since no existing backend is strict about
the feature negotiation.  But it's possible to imagine a future feature
which completely changes how a device operates: in this case, we'd need
to acknowledge it before using the device.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
hifive-unleashed-5.1
Rusty Russell 2009-06-12 22:16:35 -06:00
parent 20f77f5654
commit ef688e151c
1 changed files with 4 additions and 3 deletions
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7
drivers/virtio/virtio.c
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@ -118,13 +118,14 @@ static int virtio_dev_probe(struct device *_d)
if (device_features & (1 << i))
set_bit(i, dev->features);
dev->config->finalize_features(dev);
err = drv->probe(dev);
if (err)
add_status(dev, VIRTIO_CONFIG_S_FAILED);
else {
dev->config->finalize_features(dev);
else
add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
}
return err;
}