James Bottomley <James.Bottomley@xxxxxxxxxxxx> wrote on 06/06/2005 17:32:53: > On Mon, 2005-06-06 at 11:32 +0300, Liran Schour wrote: > > In order to run our OSD SCSI initiator on top of the Linux SCSI layer > > we have needed to do the following changes to the SCSI code: > > 1. Redefine MAX_COMMAND_SIZE to 256 byte. > > There's more than just you interested in this one, so separating this > feature out from all the rest would be helpful. > > > 2. Define a new scatter gather structures that includes two virtual buffers > > on for data out and one for data in. (implementing bidirectional > > commands) > > The SCSI middle layer doesn't now this new structure (only ULD and LLD). > > Yes, this is the nasty one ... and why OSD hasn't been incredibly > popular; bidirectional commands necessitate fairly sweeping changes to > all LLDs to support. However, I don't see how we can get away without > the mid-layer knowing, since it's the entity that constructs the sglists > and the sglists have to be separated between the in and out pieces. > In our driver we build both sg lists ( IN and OUT) in the OSD driver (ULD) and send it to the middlayer via scsi_do_req. - Liran - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
