[OpenPower-Firmware] Dropping Power8 in op-build

[Klaus Heinrich Kiwi]

On 6/17/2020 1:41 PM, Stewart Smith wrote:
> 
>> On Jun 17, 2020, at 4:54 AM, Klaus Heinrich Kiwi <klaus at linux.vnet.ibm.com> wrote:
>>
>>> On 6/17/2020 4:58 AM, Joel Stanley wrote:
>>>> On Wed, 17 Jun 2020 at 05:38, Paul Menzel
>>>> <pmenzel+openpower-firmware at molgen.mpg.de> wrote:
>>>> It looks like they are held up due to failing in IBM internal build
>>>> environment. Can that internal environment be integrated into the public
>>>> CI infrastructure?
>>> If the reason we can't merge is internal CI fails to build, won't that
>>> same internal CI fail to build if we remove Power8 from the tree and
>>> update to the newer compilers?
>>
>> I think Dean and Dan can better comment on this, but my take is that the Hostboot team
>> (as well as SBE, OCC etc) have a Power8 branch, on which we based several of our products,
>> and they're maintaining that branch as those products still require them. Since those are
>> long-term products in "fixes" mode only, they'd prefer not to change the toolchain
>> from underneath it, adding risk to existing products using them and essentially having
>> to re-validate all of them end-to-end.
> 
> That should have nothing to do with upstream master though.

Fact is that our op-build master still depends on that -p8 branch

> 
> I’d also note that the try-cflag patch that Joel proposed (a cherry pick of my four year old patch) would solve this problem anyway.

I guess even Cherry-picking those are considered to be requiring extensive testing in the -p8 branch.
Existing products in maintenance mode are not wanting to mess with their toolchains, specially due to a demand outside
those product's scope.


>>> I can't see the downside to merging these patches in. There's no
>>> guarantee of support or testing, but it allows folks like Paul to
>>> still build from master, and take advantage of updates to skiboot,
>>> buildroot and Linux.
>>
>>
>> I believe it would require the HB, OCC, SBE teams etc to perform "a branch of a branch",
>> i.e., continue to maintain the branch in which we have products still in service,
>> while creating a new branch, that sits somewhere in between "hostboot-p8" and
>> "hostboot-master", that is able to drive the Power8 chip while still tolerating newer
>> compilers and toolchains (and new features?).
> 
> Hostboot master is wildly different from Hostboot master-p8.
> 
> We’re talking a dozen patches here.

I guess one or a hundred patches, it's the concept that is being discussed here. I believe our group within
IBM is in practice not equipped to maintain another -p8-derivate branch, in addition to -p8 itself and master.

I played around with that "Alternate Toolchain" PRs exactly for that reason, but even if we could use that mechanism,
I don't think we'd have anyone from IBM maintaining the -p8-derivate branches.
  
> I’d almost encourage the community just to maintain branches ourselves, it’d be less work. IBM can pull if it wants, but perhaps it’s time to just have open power branches.
> 
> I also wonder if this pattern is about to be repeated with P9, as it has a much larger installed base out in a broader community what with the availability of the Raptor boxes.
> 

This pattern is very likely to repeat for P9, yes.

  -Klaus

-- 
Klaus Heinrich Kiwi <klaus at linux.vnet.ibm.com>