diff options
Diffstat (limited to 'virtio-v1.0-wd01-part1-specification.txt')
| -rw-r--r-- | virtio-v1.0-wd01-part1-specification.txt | 84 |
1 files changed, 6 insertions, 78 deletions
diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt index c26fea2..ba08d49 100644 --- a/virtio-v1.0-wd01-part1-specification.txt +++ b/virtio-v1.0-wd01-part1-specification.txt @@ -1715,85 +1715,13 @@ virtio: #define CCW_CMD_WRITE_CONF 0x21 #define CCW_CMD_WRITE_STATUS 0x31 #define CCW_CMD_READ_VQ_CONF 0x32 -#define CCW_CMD_SET_VIRTIO_REV 0x83 2.3.3.2. Device Initialization ------------------------------ virtio-ccw uses several channel commands to set up a device. -2.3.3.2.1. Setting the Virtio Revision --------------------------------------- - -CCW_CMD_SET_VIRTIO_REV is issued by the driver to set the revision of -the virtio-ccw transport it intends to drive the device with. It uses the -following communication structure: - -struct virtio_rev_info { - __u16 revision; - __u16 length; - __u8 data[]; -}; - -revision contains the desired revision id, length the length of the -data portion and data revision-dependent additional desired options. - -The following values are supported: - ------------------------------------------------------------------- -| revision | length | data | remarks | -|----------|--------|-----------|--------------------------------| -| 0 | 0 | <empty> | legacy interface; transitional | -| | | | devices only | -|----------|--------|-----------|--------------------------------| -| 1 | 0 | <empty> | Virtio 1.0 | -|----------|--------|-----------|--------------------------------| -| 2-n | | | reserved for later revisions | ------------------------------------------------------------------- - -Note that a change in the virtio standard does not neccessarily -correspond to a change in the virtio-ccw revision. - -A device must post a unit check with command reject for any revision -it does not support. For any invalid combination of revision, length -and data, it must post a unit check with command reject as well. A -non-transitional device must reject revision id 0. - -A driver should start with trying to set the highest revision it -supports and continue with lower revisions if it gets a command reject. - -A driver must not issue any other virtio-ccw specific channel commands -other than CCW_CMD_VDEV_RESET prior to setting the revision. - -A device must answer with command reject to any virtio-ccw specific -channel command that is not contained in the revision selected by the -driver. - -After a revision has been successfully selected by the driver, it -must not attempt to select a different revision. A device must answer -to any such attempt with a command reject. - -A virtio reset via CCW_CMD_VDEV_RESET resets the selected revision. -After a reset, the device must react to commands as if no revision had -been selected before. - -2.3.3.2.1.1. Legacy Interfaces: A Note on Setting the Virtio Revision ---------------------------------------------------------------------- - -A legacy device will not support the CCW_CMD_SET_VIRTIO_REV and answer -with a command reject. A non-transitional driver must stop trying to -operate this device in that case. A transitional driver must operate -the device as if it had been able to set revision 0. - -A legacy driver will not issue the CCW_CMD_SET_VIRTIO_REV prior to -issueing other virtio-ccw specific channel commands. A non-transitional -device therefore must answer any such attempts with a command reject. -A transitional device must assume in this case that the driver is a -legacy driver and continue as if the driver selected revision 0. This -implies that the device must reject any command not valid for revision -0, including a subsequent CCW_CMD_SET_VIRTIO_REV. - -2.3.3.2.2. Configuring a Virtqueue +2.3.3.2.1. Configuring a Virtqueue ---------------------------------- CCW_CMD_READ_VQ_CONF is issued by the guest to obtain information @@ -1841,7 +1769,7 @@ struct vq_info_block_legacy { queue contains the guest address for queue index, num the number of buffers and align the alignment. -100.3.3.2.2. Virtqueue Layout +100.3.3.2.1. Virtqueue Layout ------------------------------ The virtqueue is physically contiguous, with padded added to make the @@ -1861,14 +1789,14 @@ The calculation for total size is as follows: + ALIGN(sizeof(u16)*3 + sizeof(struct vring_used_elem)*num); } -2.3.3.2.3. Communicating Status Information +2.3.3.2.2. Communicating Status Information ------------------------------------------- The guest can change the status of a device via the CCW_CMD_WRITE_STATUS command, which transmits an 8 bit status value. -2.3.3.2.4. Handling Device Features +2.3.3.2.3. Handling Device Features ----------------------------------- Feature bits are arranged in an array of 32 bit values, making @@ -1895,7 +1823,7 @@ For communicating its device features to the host, the guest may use the CCW_CMD_WRITE_FEAT command, denoting a features/index combination. -2.3.3.2.5. Device Configuration +2.3.3.2.4. Device Configuration ------------------------------- The device's configuration space is located in host memory. It is @@ -1911,7 +1839,7 @@ read from. In both cases, the complete configuration space is transmitted. -2.3.3.2.6. Setting Up Indicators +2.3.3.2.5. Setting Up Indicators -------------------------------- To communicate the location of the indicator bits for host->guest |