[coreboot] POWER9 / Talos II coreboot support?

[Timothy Pearson]

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On 05/03/2018 03:44 AM, Kyösti Mälkki wrote:
> On Wed, May 2, 2018 at 9:22 PM, Timothy Pearson
> <tpearson at raptorengineering.com> wrote:
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>> We've been kicking around the idea for some time of getting a coreboot
>> port to the POWER9 Talos II systems going.  We don't have the resources
>> available / free at the moment to work on this independently, but it
>> might be possible to get something going if there are other community
>> members interested in helping out.
>
> Count me in, I am getting sick and tired of x86 vendors ;)
>
> Kyösti

Sounds great, glad to have you on board!  Any other volunteers?

I've created a Wiki page where we can start tracking at least what needs
to be done, and most importantly start documenting the various chunks of
hardware that coreboot needs to set up [1].  It's preloaded with what I
am sure is a very optimistic list of tasks; contributions are welcome as
we iron out exactly what is involved here.

I'd like to see what kind of manpower we can attract on-list here, then
schedule some meetings around the best approach to the initial bringup.
 We can also figure out how to handle getting hardware access to the
various folks involved.  I don't know how much of the initial work is
more practical in e.g. qemu versus on bare metal, given the complexity
of some of the existing firmware stage handoffs.  At minimum we should
start documenting the entry and exit interfaces between
SBE<-->coreboot<-->skiboot, along with expected processor state at
entry/exit, to see what we're getting involved in.

On the plus side we have direct access to LPC via the nest, and a BMC
that receives LPC accesses including serial and port 80 traffic.  This
should make debugging fairly easy, once enough of a bootblock has been
written to take over from the SBE and initialize enough of the nest to
get LPC online.  POWER9 doesn't have the concept of I/O space, so the
LPC access is all handled via MMIO reads and writes to a specific set of
addresses in the nest itself.

There's a sizeable chunk of register documentation available on the
OpenPOWER portal, although I think the detailed register manuals need an
IBM account (freely available) and possibly a (free) OpenPOWER signup.
There is no legal issue that we are aware of with using them to develop
a libre firmware solution like coreboot; IBM just doesn't want the
detailed register manuals distributed verbatim online at this time.

Let's make this happen!

[1] https://wiki.raptorcs.com/wiki/Coreboot/ToDo

- -- 
Timothy Pearson
Raptor Engineering
+1 (415) 727-8645 (direct line)
+1 (512) 690-0200 (switchboard)
https://www.raptorengineering.com
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