[Stgt-devel] tgt target drivers?

[FUJITA Tomonori]

On Tue, 6 May 2008 13:57:15 +0200
"tgt user" <tgt.user at gmail.com> wrote:

> On Tue, May 6, 2008 at 7:37 AM, FUJITA Tomonori
> <fujita.tomonori at lab.ntt.co.jp> wrote:
> >
> > On Mon, 5 May 2008 14:17:27 +0300
> > "tgt user" <tgt.user at gmail.com> wrote:
> >
> > > Hello,
> > >
> > > I was wondering - what is the status of the target drivers in tgt? I know
> > > that iSCSI is available. What about the rest? What is their status?
> >
> > First, use the plain text format. I often ignore html mails.
> Sure. I hope it is ok now. If not, I'll try to re-config my Gmail account.

ok.


> > - iSCSI and iSER drivers should work.
> >
> > - IBM pSeries virtual scsi target driver should work
> >
> > - FCoE driver is available but not tested well.
> >
> > - I submitted qlogic 2x00 fc driver several monthes ago but I guess
> > that Qlogic is not eager to support it.
> Thank you.
> 
> The FC driver is kernel code, right?

Yes, IBM pSeries driver and qla2xxx drivers run in user space.


> Was it accepted?

The qla2xxx driver isn't.


> Which support does it need from Qlogic?

We need ACK from Qlogic to push it to mainline because the target
driver works with the mainline qla2xxx initiator driver.

We also need thier technical help like the details of the hardware and
firmware. Without such help, it's impossible to implement and keep the
driver reliable.


> Can you direct me to the stgt FC code in the kernel tree?

Here's a patch:

http://marc.info/?l=linux-scsi&m=118857984513557&w=2

However, it doesn't work anymore since the qla2xxx initiator driver
has changed lot.


> Another question - I think that I understand more or less the
> userspace code. Can you say a few words about scsi_tgt_lib.c &
> scsi_tgt_if.c and how it interacts with userland?

In short, they share a ring buffer for bi-directional communiction.

A similar and simpler exmaple is net/packet/af_packet.c
(CONFIG_PACKET_MMAP) though it's not bi-directional communiction
(only kernel -> user space).

Another similar example is Xen's blktap, storage virtualization
mechanism. It works like tgt.