[ewg] Re: Distributing the SRP target source code

[Bart Van Assche]

On Jan 28, 2008 6:07 PM, Vu Pham <huongvp at yahoo.com> wrote:
>
> On srpt readme file, the prerequisite is install SCST BEFORE
> ofed-1.3 or like Vlad warning "recompiling ofed" if you
> install scst after install ofed.

This is what will happen if someone installs Linux kernel headers +
SCST + OFED in this order:
1. Linux kernel headers matching the running kernel are installed in
/usr/src/linux-.../include or equivalent, and a symbolic link to the
kernel headers is created in /lib/modules/$(uname -r)/build/include.
2. By building and installing SCST, SCST modules are installed in
/lib/modules/$(uname -r)/extra and SCST kernel headers are installed
in /usr/local/include, a.o. SCST's scsi_tgt.h header file, the
interface between SCST and mid-level SCSI drivers.
3. Next, OFED kernel modules are being built. During this process the
SRP target module is compiled with the header file
drivers/infiniband/ulp/srpt/scsi_tgt.h. The version of this file
distributed with OFED 1.3 is incompatible with the one distributed
with the latest version of SCST. Or: the kernel will probably crash as
soon as one starts using the SRP target module, even if he or she
followed the above outlined "official" build procedure. Including
/usr/local/include/scsi_tgt.h in the SRP target module is not an
option -- kernel modules must not include userspace headers, except
for the well known exceptions like <stdarg.h>.

All this trouble can be avoided by distributing the SRP target code
with SCST instead of with OFED.

Furthermore, all kernel headers that define inter-module interfaces
should reside in <kernel source root dir>/include/<subdir>/...  The
SRP target breaks this convention by having a private copy of an
inter-module interface in a local directory
(drivers/infiniband/ulp/srpt/scsi_tgt.h).


> here is one of the reason srpt is part of ofed not scst:
>
> SCST is GPL
> ofed + srpt is GPL or BSD

This is not an issue -- if you have a look at the Linux kernel, you
will see that all source files are licensed under at least the GPLv2
and some source files are licensed under GPLv2 + one or more other
licenses, e.g. BSD.

Bart.