dcdbas driver question

Srinivas_G_Gowda at Dell.com Srinivas_G_Gowda at Dell.com
Thu Jan 14 03:34:18 CST 2016


Thanks Pali. I missed noticing that comment in the code. I cant find the CPU# restriction in any of the documents.
Not sure why the condition was put there.... may be legacy!!! Not sure :(
Let me run it through the BIOS folks and reconfirm.


Thanks,
G


On Wednesday 13 January 2016 05:21 PM, Pali Rohár wrote:
> 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"...
> 


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