[Skiboot] [PATCH] fast-boot: occ: Re-parse the pstate table during fast-boot

[Nicholas Piggin]

On Fri,  2 Feb 2018 12:32:32 +0530
Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com> wrote:

> OCC shares the frequency list to host by copying the pstate table to
> main memory in HOMER. This table is parsed during boot to create
> device-tree properties for frequency and pstate IDs. OCC can update
> the pstate table to present a new set of frequencies to the host. But
> host will remain oblivious to these changes unless it is re-inited
> with the updated device-tree CPU frequency properties. So this patch
> allows to re-parse the pstate table and update the device-tree
> properties during fast-reboot.
> 
> OCC updates the pstate table when asked to do so using pstate-table
> bias command. And this is mainly used by WOF team for
> characterization purposes.

Would this ever be used in production, I'm guessing not? I don't
think that's a bad thing as such -- designing for test is always
good. Perhaps a comment though to explain why you're re-parsing
it.

Without knowing much about OCC, I'll guess you're doing this so
you can update the OCC at runtime without having to update firmware
before each IPL?

I guess we should always keep in mind fast reboot should match IPL
as closely as possible and any undetected deviations are a pretty
serious flaw. (e.g., you mess up your OCC state and want to return
to normal, you would reboot).

I'm just wondering, should this be under an nvram option?

Thanks,
Nick