On Thu, 2010-08-19 at 23:20 +0200, Dirk Meister wrote: > Am 19.08.2010 um 03:18 schrieb jack wang: > > [Jack]Vote for SCST as a user and target driver developer based on > > SCST. > > SCST really do good job. > [dmeister] Vote for SCST. I am working with SCST to develop an user- > space target backend using the scst_user feature. > The functionality, the stability of SCST, and the wide range of target > drivers for SCST are really nice. > Just FYI, as myself and other folks do have a need for a proper target mode kernel fabric -> userspace LUN passthrough, this will be addressed by building upon Tomo-san and mnc's already existing mainline code in drivers/scsi/scsi_tgt_*.c Pretty much everything already exists there for doing a userspace target, which is then registered as a seperate TCM/STGT subsystem plugin that can be configfs symlinked into fabric module SCSI ports at will with full SPC-3 PR and ALUA support for all supported TCM fabric modules. The complete discussion for that is mentioned in this thread: http://lkml.org/lkml/2010/5/27/672 Here is the 'meat' of the discussion, which is mentioned in the context of the '2nd phase of STGT <-> LIO compatibility': "We will be extending the scsi_tgt_[lib,if].c mapped ring interface to allow TCM to access userspace backstores transparently with existing kernel level TCM fabric modules, and using the generic configfs fabric module infrastructure in target_core_fabric_configfs.c for the port and I_T nexus control plane just as you would with any TCM backstore subsystem today. Again, in open source you have to build upon what already exists and move forward. The original STGT kernel <-> userspace ring abstraction and logic in drivers/scsi/scsi_tgt_lib.c:scsi_tgt_queue_command() -> scsi_tgt_uspace_send_cmd() is already going to do the vast majority of what is required for handling fabric I/O processing and I_T Nexus and Port management in kernel space with a userspace backstore. It is really just a matter of allowing the STGT ring request to optionally be sent out to userspace as a standalone LUN instead of as a target port." Note this code was left out of the last postings on linux-scsi, and will most likely be left out initially for v2.6.37. I do plan to have something up and running on lio-core-2.6.git for one of my QEMU-KVM projects by then however. Here is how the code currently looks: http://git.kernel.org/?p=linux/kernel/git/nab/lio-core-2.6.git;a=blob;f=drivers/target/target_core_stgt.c;hb=refs/heads/lio-4.0 Best, --nab -- 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
