[ewg] Re: [ofa-general] resolve conflict between OFED 1.3 and 2.6.18 with ISCSI

[Erez Zilber]

Brian J. Murrell wrote:

> I have run into a conflict trying to build a matching kernel and
> kernel-ib pair for OFED 1.3 and RHEL5's 2.6.18 kernel (although I
> suspect this will apply to generally any kernel of the same vintage).
>   

General comment - in the future, I suggest that you send OFED related
e-mails also to the EWG list and to me (I maintain iSER in OFED &
kernel.org).

> The problem is that OFED 1.3 appears to include/provide some iSCSI
> support, such as drivers/scsi/scsi_transport_iscsi.c for one example
> which is the "SCSI_ISCSI_ATTRS" kernel attribute.  The 2.6.18 RHEL5
> kernel can provide the same capability if one decides to configure it
> into the kernel build.
>   

OFED 1.3 provides open-iscsi 2.0-865.15 (userspace & kernel). This
version is newer than the version that is shipped with RHEL5. It also
has full iSER support.

> So the question arises, do I want to have the kernel provide it or have
> kernel-ib provide it.  It's not quite that easy though.
>
> If I disable it in the kernel, I also disable dependent drivers such as
> SCSI_QLA_ISCSI (QLogic ISP4XXX host adapter family support).  In order
> to disable it in the kernel-ib build I need to disable "iser" support
> with "--without-iser-mod", which seems a bit like throwing the baby out
> with the bathwater.
>   

Yeah, it is an open-iscsi transport, so you must have open-iscsi in
order to use this driver. With OFED 1.3, qla4xxx is not included. We
only included the TCP & iSER transports.

> The reason I need to disable this in one place or another is that if my
> kernel RPM is providing scsi_transport_iscsi.ko and so is kernel-ib, I
> get an RPM conflict as the two files are in the same location in
> the /lib/modules/$(uname -r) tree.
>   

Of course. You can't have open-iscsi modules twice.

> So how to resolve?  I don't think it can be resolved easily currently.
> I think the ofa_kernel build system needs to be more intelligent about
> what's selected in the kernel and not providing duplicate capabilities.
> IOW, I should be able to select CONFIG_SCSI_ISCSI_ATTRS=m in my
> kernel .config and CONFIG_INFINIBAND_ISER=m in my ofa_kernel
> configuration and ofa_kernel should figure out if it needs to provide
> SCSI_ISCSI_ATTRS (i.e. build scsi_transport_iscsi.ko) or whether the
> kernel is configured to and will be providing it.
>   

OFED is shipped with its own version of open-iscsi because I don't want
to support multiple versions of open-iscsi (each distro has its own
version of open-iscsi). Also, having a newer version of open-iscsi
(which we have in OFED) fixes many bugs and adds new features (which is
good).

Is qla4xxx the only problem that you have with open-iscsi in OFED?

Erez