[Skiboot] [PATCH v3 6/6] platform: Identify correct bmc platform based on bmc hw version

[Nicholas Piggin]

On Tue Feb 18, 2025 at 4:39 PM AEST, Mahesh J Salgaonkar wrote:
> On 2025-02-18 11:33:53 Tue, Nicholas Piggin wrote:
>> On Thu Feb 6, 2025 at 11:56 PM AEST, Mahesh Salgaonkar wrote:
>> > At the moment the generic platform sets bmc_generic() as bmc platform
>> > which does not have any support to initialize the flash and hence it
>> > fails to load petitboot kernel.
>> >
>> > [  583.105000325,4] FLASH: Failed to load VERSION data
>> > [  583.105490257,5] INIT: Waiting for kernel...
>> > [  583.105523156,5] INIT: platform wait for kernel load failed
>> > [  583.105555219,5] INIT: Assuming kernel at 0x20000000
>> > [  583.105589925,3] INIT: ELF header not found. Assuming raw binary.
>> > [...]
>> > [  583.299682673,5] INIT: Starting kernel at 0x20000000, fdt at 0x30a44eb0
>> > 1274673 bytes
>> > [  583.344432417,3] ***********************************************
>> > [  583.344490230,3] Fatal Exception 0x800 at 0000000020000000
>> > MSR 9000000000000000
>> > [  583.344535875,3] CFAR : 0000000030022948 MSR  : 9000000000000000
>> > [  583.344578019,3] SRR0 : 0000000020000000 SRR1 : 9000000000000000
>> > [  583.344620242,3] HSRR0: 0000000020000000 HSRR1: 9000000000000000
>> >
>> > OPAL builds the device tree for BMC based system using HDAT. It
>> > populates bmc/compatible node with bmc hw version e.g.
>> > "ibm,ast2600,openbmc". Use that to identify proper BMC hw board and
>> > initialize BMC platform with proper backend. This allows opal to
>> > successfully load and boot into petitboot kernel.
>> 
>> Interesting hack. So you need this because there no real platform
>> for P11 yet? I'd almost rather rip the generic stuff out entirely, it
>> looks like you'll miss the power down and some other things for
>> example.
>
> Yes, until we have real platform GA'ed this will get us booted with
> linux kernel sucessfully.
>
>> 
>> If you're finding it useful for now then okay, but would be nice to
>> have a platform for it.
>
> We do have a platform patch ready but not sure whether I should post it
> out before HW gets GA'ed. I am not sure how we did this in past for
> Power10 rainier platform, before GA or after GA.

That's okay, leave it out for now and we'll go with this generic one.

Thanks,
Nick