dcdbas driver question

Pali Rohár pali.rohar at gmail.com
Wed Jan 13 05:51:37 CST 2016

On Wednesday 13 January 2016 17:03:05 Srinivas_G_Gowda at Dell.com wrote:
> >>> In the SUSE SLES Xen kernel we are carrying a patch for the dcdbas
> >>> driver to ensure a SMI is triggered on physical cpu 0 only. This
> >>> requires to use some Xen interfaces in the kernel which are not
> >>> part of the stable Xen API (this is the reason they have never been
> >>> upstreamed).
> >>>
> >>> We are now moving to a pvops kernel requiring to either port those
> >>> patches to pvops (and possibly upstream them) or to drop them in
> >>> case they are no longer needed.
> >>>
> >>> Are you able to tell me which Dell machines require a SMI to be
> >>> triggered on cpu 0? As my current Dell laptop is running with the
> >>> pvops kernel on top of Xen just fine, I guess not all Dell machines
> >>> have this requirement.
> >>>
> >>
> >> I believe there is no such restrictions. You should be able to get a valid response immaterial of which CPU issues the SMI.
> > 
> > So dcdbas_smi_request() should be changed to not bind the running
> > thread to cpu 0? In case you confirm, I can set up a patch doing
> > this.
> > 
> Yes, you don't need to have an affinity for CPU0.

Really? Code in commit 90563ec4129f14d19f018240d1d3ff5c0e5e6392
of linux git tree explicitly says that "SMI requires CPU 0"...

Pali Rohár
pali.rohar at gmail.com

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