Re: FreeBSD on PowerVM LPARs (powerpc64le) — LibrePower PoC

Le 2026-08-17T16:27:27.000+02:00, Calvin Buckley <[email protected]> a
écrit :

>  It should work on PowerVM/phyp in both LE/BE, but there's some bugs that prevent it from working[1]. If you fix one, the other one should also be fixed (and FWIW, P5/P6/P7 hardware is cheap used and BE only).
>  
> [1]: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=279137

Thanks Calvin — that bug report is useful, and I had not seen it
before.

I encountered a failure at the same stage: boot1.chrp never reached
the loader on real PAPR firmware. In my case, the problem seemed to be
the entry convention. The firmware enters the client program in
big-endian mode, while boot1.elf is a little-endian image whose entry
point does not switch MSR[LE]. As a result, the first instruction is
decoded using the wrong endianness and traps.

This does not happen under QEMU because SLOF enters client programs in
little-endian mode. The proposed fix is a short bi-endian preamble at
_start, using the same approach as Linux’s FIXUP_ENDIAN:

https://gitlab.com/librepower/freebsd-powervm/-/blob/main/patches/12-01-boot1-endianness.patch

There is one important caveat regarding PR 279137: the preamble is
compiled only for little-endian builds. Big-endian images already
match the PAPR entry convention, so I think this shall not explain the
BE failures described in that report. It may explain one part of the
problem, but someone with an affected system should be able to confirm
or rule it out quickly.

Regarding older hardware, I understand the point. However, my target
is a PowerVM partition on "current" systems (Power9/10/11) both
on-premises and PowerVS.

In any case, I will keep documenting and publishing everything in the
repository, whether or not it eventually reaches upstream. If it helps
someone investigate the remaining issues, test on other systems, or
submit better patches, then this modest effort will already have been
worthwhile.