[Design] PSU firmware update

[Alexander Amelkin]

04.06.2019 5:58, Lei YU wrote:
> On Tue, Jun 4, 2019 at 1:23 AM Neeraj Ladkani <neladk at microsoft.com> wrote:
>> 1. Why host power off is a pre-condition? We should add this a PSU pre-requisite to support Live upgrade and activation.
> Derek's reply explains the reason why we want to the host power off as
> pre-condition.
>
>> 2. How should PSU update impact PSU and battery monitoring ? should there be coordination between sensor monitoring task during update ?
> This is a good point. During PSU update, the driver probably should be unbind,
> and after the update is one, rebind the driver.
> Does that sounds OK?

Unbinding the telemetry driver (as in kernel driver) isn't a good idea because telemetry for a PSU can be provided by the same driver that provides firmware update facilities.

In YADRO we have developed a mechanism that renders certain sensors 'invalid' (or alternatively changes their thresholds) in certain states of other sensors. For us that allows for avoiding failure state for chassis fan sensors when the host is off and also let's us live fine with zero main 12V output of PSUs when the host is off. I suppose this mechanism could be adopted by OpenBMC and adapted to this task to just disable some telemetry during PSU firmware update.

>
>> 3. PSU may have multiple regions like bootloader, active region and inactive region. We should design to support multiple region update.
> I do not have detailed information about this, which is more suitable to let
> the vendor-specific tool to handle the multiple regions.
> What do you think?

It's definitely up to the PSU vendor specific update tool to handle all the layout and update interface peculiarities.

>
>> 4. Can you propose required SEL logs and telemetry requirements as well ?
> While I was writing this design doc, I was not thinking about the detailed SEL
> logs.
> Will need some time to discuss this and see if it shall be covered in this doc
> or not.

The only event that I could find in IPMI spec is 'Version change' (sensor type code 0x2B).

With best regards,
Alexander Amelkin,
Leading BMC Software Engineer, YADRO
https://yadro.com



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