Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support

[Christoph Hellwig]

On Thu, Apr 30, 2009 at 10:49:19PM +0100, Paul Brook wrote:
> Only if you emulate a crufty old parallel scsi bus, and that's just silly.
> One of the nice things about scsi is it separates the command set from the 
> transport layer. cf. USB mass-storage, SAS, SBP2(firewire), and probably 
> several others I've forgotten.

It has nothing to do with an SPI bus.  Everything that resembles a SAM
architecture can have multiple LUs per targer, and multiple targers per
initiator port, so we need all the complex queing code, and we need
error handling and and and.  For some really simple ones like USB
mass-storage we might get away with some ad-hoc SCSI CDB generation
instead of real scsi stack, but I would recommend against it.