Re: [RFC v1 0/4] ipmi_bmc: framework for IPMI on BMCs

[Brendan Higgins]

On Mon, Aug 14, 2017 at 3:28 PM, Brendan Higgins
<brendanhiggins@xxxxxxxxxx> wrote:
> On Mon, Aug 14, 2017 at 7:03 PM, Patrick Williams <patrick@xxxxxxxxx> wrote:
>> On Mon, Aug 07, 2017 at 08:52:57PM -0700, Brendan Higgins wrote:
>>> Currently, OpenBMC handles all IPMI message routing and handling in userland;
>>> the existing drivers simply provide a file interface for the hardware on the
>>> device. In this patchset, we propose a common file interface to be shared by all
>>> IPMI hardware interfaces, but also a framework for implementing handlers at the
>>> kernel level, similar to how the existing OpenIPMI framework supports both
>>> kernel users, as well as misc device file interface.
>>
>> Brendan,
>>
>> Can you expand on why this is a good thing from an OpenBMC perspective?
>
> Sure, so in addition to the individual handlers; this does introduce a
> common file
> system interface for BMC side IPMI hardware interfaces. I think that is pretty
> straightforward.
>
> Corey and I are still exploring the handlers. My original intention
> was not to replace
> any of the handlers implemented in userspace. My motivating use case is for some
> OEM commands that would be easier to implement inside of the kernel.
>
> I was hoping to send out an overview of that, but the internet in my
> hotel sucks,
> so I will do it the next time I get decent internet access. :-P

I was able to get this out on Monday on the OpenBMC mailing lists:
https://lists.ozlabs.org/pipermail/openbmc/2017-August/008861.html

>
> In any case, Corey raised some interesting points on the subject; the
> most recent
> round I have not responded to yet.
>
>> We have a pretty significant set of IPMI providers that run in the
>> userspace daemon(s) and I can't picture more than a very small subset
>> even being possible to run in kernel space without userspace assistance.
>
> Like I said, I have an example of some OEM commands. Also, as I have said,
> my intention is not to replace any of the userland stuff. That being said, I am
> not sure the approach we have taken so far is the best when it comes to some
> of the new protocols we are looking at like IPMB and MCTP. Having some
> consistency of where we draw these interface boundaries would be nice; so
> maybe that means rethinking some of that. I don't know, but it sounds like
> Corey has already tried some of this stuff out on his own BMC side
> implementation.
>
> Regardless, I think there is a lot of interesting conversation to be had.
>
>> We also already have an implementation of a RMCP+ daemon that can, and
>> does, share most of its providers with the host-side daemon.
>
> That's great. Like I said, my original intention was not to rewrite any of that.

Corey had a good point about this in my thread with him. I made a proposal
of what to do there.

>
>>
>> --
>> Patrick Williams
>
> By the way, Corey suggested that we have a BoF session at the Linux Plumbers
> Conference, so I set one up:
> https://linuxplumbersconf.org/2017/ocw/proposals/4723
> I highly encourage anyone who is interested in this discussion to attend.
>
> Thanks!