Re: [PATCH 0/3] virtio-net: inline header support

Il 05/10/2012 07:43, Rusty Russell ha scritto:

quoted

quoted

    struct virtio_scsi_req_cmd {
        // Read-only
        u8 lun[8];
        u64 id;
        u8 task_attr;
        u8 prio;
        u8 crn;
        char cdb[cdb_size];
        char dataout[];
        // Write-only part
        u32 sense_len;
        u32 residual;
        u16 status_qualifier;
        u8 status;
        u8 response;
        u8 sense[sense_size];
        char datain[];
    };

where cdb_size and sense_size come from configuration space.  The device
right now expects everything before dataout/datain to be in a single
descriptor, but that's in no way part of the spec.  Am I missing
something egregious?

Since you wrote it, I hope not :)

Yeah, I guess the confusion came from cdb_size and sense_size being in
configuration space.

That's good.  But virtio_blk's scsi command is insoluble AFAICT.  As I
said to Anthony, the best rules are "always" and "never", so I'd really
rather not have to grandfather that in.

It is, but we can add a rule that if the (transport) flag
VIRTIO_RING_F_ANY_HEADER_SG is set, the cdb field is always 32 bytes in
virtio-blk.

Paolo