On 08/18/2009 01:35 PM, Madhavi Manchala wrote: > On Tue, Aug 18, 2009 at 3:30 PM, Boaz Harrosh<bharrosh@xxxxxxxxxxx> wrote: > > Dear Boaz, > > Thanks a lot. > >>> Do I need to modify the SCSI driver files to handle the >>> bi-directional comamnds or Is this already supported? >>> >> >> Yes only very few drivers support bidi commands. >> i.e. iscsi is the only one that supports them in general. > > Currently, I am registering my driver to the SCSI layer. Now I > understand, I need to register my driver to iscsi to get > bi-directional commands. If this is the case, how can I register my > driver to iscsi driver to get bi-directional commands, and will I get > the same functionality from iscsi as I am currently getting from scsi. > No!. You miss understood. iscsi is just a scsi LLD (Low Level Driver) just as usb/storage/scsiglue.c is an LLD. You only register with scsi. scsi-ml has full support for bidi. Only the LLDs do not. except two LLDs: iscsi and scsi_debug. >> (Tell me if you need example code for bsg use in user-mode). > > Could you please send me the link to the user mode bsg initiator code > which issues the bi-directional commands? > Start here: http://git.open-osd.org/gitweb.cgi?p=open-osd.git;a=blob;f=lib/bsgdev.c;h=f55a87879784f05950e7a2d88798605183cc660a;hb=ec34ca8bdef55a47c3b1f82b1021609570ccb283 and generally inspect this folder: http://git.open-osd.org/gitweb.cgi?p=open-osd.git;a=tree;f=lib;h=5739f66f529c010755ab4bb05db4496d0ea4b229;hb=ec34ca8bdef55a47c3b1f82b1021609570ccb283 Above files are used to issue scsi-osd commands from user-mode, which can all be bidi. >>> I found only one struct scsi_data_buffer pointer in scsi_cmnd >>> structure. So, how do SCSI layer sends IN and OUT buffer pointers and >>> their lengths to my class driver? >>> >> >> Again: >> if (scsi_bidi_cmnd(cmnd)) { >> in_sdb = scsi_in(cmnd); >> out_sdb = scsi_out(cmnd); >> } >> It works, look at the code. > > Before using the above snippet in my class driver, do I need to fill > in_req and out_req in SCSI layer or Is it already filled? If I use the > iscsi driver, then there is no need to do any modifications to the > in_req and out_req. > Again: upper layers have full support. You only need the top most initiator and a supporting LLD. [ Initiator => block-layer => scsi-ml => LLD - initiators: bsg and osd support bidi. All other do not. - block-layer && scsi-ml fully support bidi. - LLDs: only iscsi currently supports bidi. ] > Thanks and Regards, > Madhavi M. Boaz -- To unsubscribe from this list: 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
