target driver question

[Mark Terribile]

Mahesh,

> I am working on the master's project and would like to do on Linux fiber
> channel target emulator.is there source code for this which I can work
> on ..or download site where I can test. please suggest as to how should
> I go in implementing this.

The problem with Linux and target mode is that there are at least two parts
to a target mode solution.  You need the ability to operate the interface
card's target mode capabilities, but you also need the SCSI target mode
framework from which to operate them.  The latter is what Linux lacks, and
the direction(s) the Linux developers have chosen for their overall SCSI
architecture will make it difficult to create one.  Getting it accepted
by the guardians of the Linux source tree is a further hurdle, but one that
would be a major contribution (IMO), since it would serve the writers of ALL
SCSI device drivers.  The Linux people have chosen to replace the CAM reference
model with something else, and the contribution that CAM makes to FreeBSD's
SCSI architecture is not there.

Here are some places to start: look at the isp(4) driver, which has (or had)
a device interface level shared between Linux and FreeBSD.  See how the
target mode code works with the FreeBSD target mode facilitiies and then
see what is lacking in Linux.  I spent over a month trying to make the pieces
line up, but you might have more time; I don't know.  Google the web and the
newsgroups for 'linux scsi target mode' and pick up some of the discussions
about the subject.  Check out the code from the University of New Hampshire's
Interoperability Lab.  They are concentrating on iSCSI-over-FC, and neglecting
actual SCSI work, but you may pick up some clues.

Good luck.  I'd be glad to hear how your work turns out.

    Mark Terribile


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