Date: Wed, 17 Sep 2003 12:42:42 -0700 (PDT) From: Nate Lawson <nate@root.org> To: Chuck Tuffli <chuck_tuffli@agilent.com> Cc: freebsd-scsi@freebsd.org Subject: Re: difference between scsi_target and scsi_targ_bh Message-ID: <20030917124026.Q12649@root.org> In-Reply-To: <20030917173211.GB37253@cre85086tuf.rose.agilent.com> References: <20030917173211.GB37253@cre85086tuf.rose.agilent.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, 17 Sep 2003, Chuck Tuffli wrote: > I'm in the process of trying to understand how the targ(4) emulator > works from top to bottom and ran into some confusion over > scsi_target.c vs. scsi_targ_bh.c. From Nate's README, it appears that > you need both of these drivers for the target to work. What confuses > me is that there seems to be some hefty overlap between the two. For > example, the LUN enable/disable code is almost identical, the > constructors are similar, and the "start" functions are similar. > > My questions are > 1) are both scsi_target and scsi_targ_bh needed > 2) if so what is the general difference > > Thanks! The scsi_target kernel driver enables target mode and then passes CCBs back and forth between a userland component. The scsi_targ_bh driver auto-attaches to any LUNs that are enabled but don't have a listener. It returns valid "device not here" reponses. On isp(4), for instance, you can't just enable one LUN. The firmware enables all LUNs when it gets an enable commands. The scsi_targ_bh device handles the LUNs that you didn't really want. -Nate
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20030917124026.Q12649>