virtio_blk_req.data size - Section 5.2.6 - version 1.1 draft 01

["Savir, Gil" <gil.savir@intel.com>]

In version 1.1 draft 01 - Section 5.2.6 - struct virtio_blk_req definition:

Data field is defined as array of 512 Byte entries as follows:
	u8 data[][512];
It makes sense for IN and OUT requests, since defined for read/write sizes that are 512 Bytes multiplication.
However, it is confusing when used for DISCARD or WRITE_ZEROES requests, since virtio_blk_discard_write_zeroes struct size is 16 Bytes.

Is implying that DISCARD and WRITE_ZEROES requests must use data-field sizes that are 512 Bytes multiplication as well?

If yes, than the device can't tell how many virtio_blk_discard_write_zeroes structs reside within data-field. In that case - indication for number of virtio_blk_discard_write_zeroes structs needs to be added.

If not, then I suggest to add to the spec clarification, that for DISCARD or WRITE_ZEROES requests, data-field is not required to be with size that is 512 Bytes multiplication.


Thanks,
Gil


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