Re: Default force_link_speed value in opensm configuration

Ira Weiny
2009-10-12T21:35:53Z

On Mon, 12 Oct 2009 11:47:37 +0200
"Eli Dorfman (Voltaire)" <dorfman.eli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> Ira Weiny wrote:
> > On Tue, 06 Oct 2009 17:56:01 +0200
> > "Eli Dorfman (Voltaire)" <dorfman.eli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >
> >> Hi,
> >>
> >> Is there a reason for setting default force_link_speed to 15 (set enabled as supported)
> >> and not to 0 (don't modify PortInfo:LinkSpeedEnabled )?
> >
> > The thought was to enable all ports to the maximum supported by default. This
> > was the behavior before this option was added so it was though to leave it
> > alone by default.
> >
> > Is there a reason this should not happen? I guess since the Volume 2 spec
> > says that the power on default for this is LinkSpeedSupported there is no
> > reason to have the SM send these Set's. Perhaps there is broken hardware out
> > there?
>
> well actually there is a hardware that supports only 5.0Gbps (but reports 2.5 or 5.0 Gbps since there is no option for 5.0 only)
> and powers on with enabled speed of 5.0Gbps only.
> Setting the enabled speed to the supported speed will fail further negotiation (after link reset) since the device does not support 2.5Gbps.

That seems like broken hardware...

>
> So if the default for all other devices is enabled=supported then we can change the opensm configuration force_link_speed to 0.
>

I have no problem changing it. As I said if hardware is compliant I think it
might speed things up. I will test out a patch with the hardware I can test.

However, I would like to know if anyone else knows of hardware which needs it
set to "15". If so, this is going to be an interesting problem... ;-)

Ira

--
Ira Weiny
Math Programmer/Computer Scientist
Lawrence Livermore National Lab
925-423-8008
weiny2-i2BcT+NCU+M@public.gmane.org