Boot failure with ppc64 port on iMacs G5

[John Paul Adrian Glaubitz]

Hi Michael,

On Wed, 2024-03-06 at 12:57 +1100, Michael Ellerman wrote:
> > Yep, the second, older image works as expected. However, the recent one does not
> > and I have absolutely no clue why.
> 
> I actually tested both, and both work, but then I cited the wrong one in
> my email >_<
> 
> So at least on qemu that newer kernel is OK:
> 
>   Preparing to boot Linux version 6.6.15-powerpc64 (debian-kernel at lists.debian.org) (gcc-13 (Debian 13.2.0-13) 13.2.0, GNU ld (GNU Binutils for Debian) 2.42) #1 SMP Debian 6.6.15-2 (2024-02-04)
>   ...
>   Booting Linux via __start() @ 0x0000000004800000 ...
>   Hello World !
>   smp_core99_probe
>   smp_core99_bringup_done
>   Starting system log daemon: syslogd, klogd.

Just as a heads-up: This particular issue is related to this patch in the Debian kernel package:

> https://salsa.debian.org/kernel-team/linux/-/blob/master/debian/patches/bugfix/powerpc/fbdev-offb-Update-expected-device-name.patch?ref_type=heads

Removing this patch unbreaks the console on PowerMac G5.

I could also reproduce this issue with the latest ppc64el image on PowerKVM:

> https://cdimage.debian.org/cdimage/daily-builds/daily/current/ppc64el/iso-cd/debian-testing-ppc64el-netinst.iso

Here is a video demonstrating the issue:

> https://people.debian.org/~glaubitz/debian-bug-1033058.mp4

And here is the corresponding bug report:

> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1085949

This issue can be easily reproduced with QEMU.

Aditi Mishra (CC'ed) is trying to reproduce the issue as well, but so far has been unsuccessful.

Adrian

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