Boot failure with ppc64 port on iMacs G5

[John Paul Adrian Glaubitz]

Hi Michael,

On Fri, 2024-03-01 at 12:56 +1100, Michael Ellerman wrote:
> OK.
> 
> That second iso boots OK for me in qemu. It boots grub and then the
> kernel loads and shows:
> 
>   Loading ...
>   OF stdout device is: /pci at f0000000/mac-io at c/escc at 13000/ch-a at 13020
>   Preparing to boot Linux version 6.3.0-1-powerpc64 (debian-kernel at lists.debian.org) (gcc-12 (Debian 12.3.0-2) 12.3.0, GNU ld (GNU Binutils for Debian) 2.40) #1 SMP Debian 6.3.7-1 (2023-06-12)
>   Detected machine type: 0000000000000400
>   command line: BOOT_IMAGE=/install/vmlinux --- quiet
>   memory layout at init:
>     memory_limit : 0000000000000000 (16 MB aligned)
>     alloc_bottom : 0000000005e70000
>     alloc_top    : 0000000030000000
>     alloc_top_hi : 0000000080000000
>     rmo_top      : 0000000030000000
>     ram_top      : 0000000080000000
>   copying OF device tree...
>   Building dt strings...
>   Building dt structure...
>   Device tree strings 0x0000000005e80000 -> 0x0000000005e80560
>   Device tree struct  0x0000000005e90000 -> 0x0000000005ea0000
>   Quiescing Open Firmware ...
>   Booting Linux via __start() @ 0x0000000002000000 ...
>   Hello World !
>   smp_core99_probe
>   smp_core99_bringup_done
>   Starting system log daemon: syslogd, klogd.
> 
> And eventually starts the installer.

Yep, the second, older image works as expected. However, the recent one does not
and I have absolutely no clue why.

> That's using no VGA, so possibly there's something wrong with the video
> setup on real hardware:
> 
>   $ qemu-system-ppc64 -nographic -vga none -M mac99,via=pmu -smp 1 -m 2G -nic user -drive file=$HOME/debian-12.0.0-ppc64-NETINST-1.2023-06-18.iso,format=raw,media=cdrom -boot d
> 
> I'll try and find time to test it on my actual G5 next week when I'm in
> the office.

The video issue can usually be worked around by disabling mode-setting or
passing other kernel options related to the video card. That's not the
main problem here though.

The problem is that the newer image doesn't boot and currently I don't know
why because installing the exact same kernel later from the package manager
into an installed system works yields a bootable system with the latest
kernel.

The installer images are built from the same kernel package which makes the
whole thing even more confusing.

I'm using debian-cd to build the installation images:

> https://salsa.debian.org/images-team/debian-cd/

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
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