aha/drivers/virtio
Rusty Russell c45a6816c1 virtio: explicit advertisement of driver features
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API: in particular, we assume that feature
negotiation is complete once a driver's probe function returns.

There is nothing in the API to require this, however, and even I
didn't notice when it was violated.

So instead, we require the driver to specify what features it supports
in a table, we can then move the feature negotiation into the virtio
core.  The intersection of device and driver features are presented in
a new 'features' bitmap in the struct virtio_device.

Note that this highlights the difference between Linux unsigned-long
bitmaps where each unsigned long is in native endian, and a
straight-forward little-endian array of bytes.

Drivers can still remove feature bits in their probe routine if they
really have to.

API changes:
- dev->config->feature() no longer gets and acks a feature.
- drivers should advertise their features in the 'feature_table' field
- use virtio_has_feature() for extra sanity when checking feature bits

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-02 21:50:50 +10:00
..
config.c
Kconfig virtio: balloon driver 2008-02-04 23:50:13 +11:00
Makefile virtio: balloon driver 2008-02-04 23:50:13 +11:00
virtio.c virtio: explicit advertisement of driver features 2008-05-02 21:50:50 +10:00
virtio_balloon.c virtio: explicit advertisement of driver features 2008-05-02 21:50:50 +10:00
virtio_pci.c virtio: explicit advertisement of driver features 2008-05-02 21:50:50 +10:00
virtio_ring.c virtio: ignore corrupted virtqueues rather than spinning. 2008-05-02 21:50:43 +10:00