[Skiboot] OPAL Spec and conformance

[Stewart Smith]

Nathan Whitehorn <nwhitehorn at freebsd.org> writes:
> On 06/10/15 15:43, Stewart Smith wrote:
>> Hi all,
>>
>> This is something I'm sending both to the System Software Workgroup at
>> OpenPower fonudation and the skiboot list as it's relevant to both
>> audiences.
>>
>> SYSSW people: note that the skiboot list is *public* to the world.
>>
>> There is a need to have an OPAL Specification as part of the OpenPower
>> effort along with a conformance test suite.
>>
>> Goal:
>> - OPAL API specification (including device-tree)
>>    - i.e. what host OS interacts with
>> - spec for petitboot environment
>>    - i.e. how you can boot an OS, what filesystems/device drivers are
>>    supported.
> [...]
>> - come up with a plan to document and standardize petitboot environment
>>    - (i.e. what can you boot from. XFS? ext4?)
>>
>>
>
> One thing that would be *extremely* helpful here is an environment to 
> run a second-stage loader. We need this for FreeBSD for a variety of 
> reasons, mostly that the boot loader is responsible for loading kernel 
> modules according to scripts rather than having a prefab initrd.
>
> On petitboot systems, the way this works now is that we ship a Linux ELF 
> executable on a FAT32 filesystem that does all the right things and then 
> calls kexec itself. This works fine except that you have to exit to a 
> shell and run it by hand since there is no way to put something in the 
> petitboot menu that does not get kexec'ed.

This is all useful to know... is it basically a "load all modules into
memory locations and then jump somewhere?"

I have to admit a fair bit of ignorance on how freebsd boots from, say
GRUB or OpenFirmware (on x86 or power).