Re: [Scst-devel] Fwd: Re: linuxcon 2010...

[Nicholas A. Bellinger]

On Fri, 2010-08-27 at 00:11 +0400, Vladislav Bolkhovitin wrote:
> Nicholas A. Bellinger, on 08/25/2010 01:23 AM wrote:
> > As mentioned explictly earlier in this thread, my WIP code for the
> > kernel level subsystem backstore using STGT kernel<->  user CDB
> > passthrough logic in drivers/target/target_core_stgt.c is a item on
> > my TODO list, but I will repeat, is NOT being tagged as a mainline
> > .37 item.
> 
> Hmm, I can't understand, if target_core_stgt.c is "NOT being tagged as a 
> mainline .37 item", then the STGT ABI compatibility for being a drop in 
> replacement for STGT isn't a requirement? Or am I missing something?
> 

Sorry, but I have no idea what you are trying to conjour up here.

To spell out (again) the TCM/LIO<->STGT compatibility stages that have
been persued pubically over the last months:

I) Create proper userspace tgt.git SG_IO and BSG passthrough into   
   TCM_Loop v4 using high-level multi-fabric WWPN emulation so that TCM 
   Core SPC-4 kernel emulation is exposed to STGT user fabrics, eg: 
   userspace fabric module -> kernel backstore passthrough.  (DONE 
   for .37, and STGT passthrough + BSG backstore support merged into 
   tgt.git by Tomo-san)

II) Complete target_core_stgt.c TCM subsystem plugin for kernel -> user 
    CDB -> LUN passthrough building upon existing 
    drivers/scsi/scsi_tgt_*.c code.  (WIP for .38, made available 
    initially as a seperate standalone .ko module in lio-core-2.6.git)

> > Tomo-san, mnc, and other storage folks have been briefed on the
> > remaining issues that would be involved to get a prototype
> > functioning with drivers/target/target_core_stgt.c, and rough idea of
> > what it would take in existing mainline drivers/scsi/scsi_tgt_*.c
> > code.  With the current WIP code this will allow the userspace CDB ->
> > LUN passthrough to function transparently with all TCM SPC-4
> > compliant logic as a standalone struct se_subsystem_api
> > tcm_core_stgt.ko backstore.
> 
> This is exactly what we are discussing.

Then I suggest you start working on a patch for drivers/scsi/scsi_tgt_*
in order to address what you believe are the preceived shortcomings of
the original design.

Until you can do that, and actually take an impartial look at the
existing drivers/scsi/scsi_tgt_*.c,  it would be a bit difficult to
beleive you genuinely want to steer our current level of interaction
away from continued hand-waving noise into a real rational technical
discourse between yourself and the LIO/STGT development community.

Best,

--nab

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