PowerBook G3 Wallstreet Hang Using Debian Kernel

Hi Cedar,

I haven't been able to determine a reason for the hang of Debian's 
default kernel/initrd combination (6.16.9+deb14-powerpc) on the PowerPC 
PowerBook G3 Series laptop (Wallstreet).

Finn Thain (cc'ed on this message) found a bug that was causing video to 
not work correctly (see "https://lkml.org/lkml/2025/10/9/639"). 
Unfortunately, as it turns out, that bug was not related to the Debian hang.

I'm able to reproduce the hang on my Wallstreet (266 MHz, 512 MiB) using 
an updated Debian SID and the Debian kernel/initrd. However, the hang 
doesn't happen on my PowerBook Lombard or Pismo. As you've reported, the 
symptoms are that the screen goes blank and the backlight stays on, and 
the system freezes (Linux doesn't boot).

And there's no output from the serial port. It's possible that there's 
an issue with BootX not being able to handle large initrd.img files 
(initrd.img-6.16.9+deb14-powerpc is over 40 MB), but I really have no 
idea. I tried adjusting the memory for BootX in Mac OS 9 to 64 MiB, but 
the hang persists. I also tried adding sccdbg and initcall_debug to the 
kernel command line, as suggested by Finn, but neither generated any 
serial output, which suggests (to me) an issue with BootX. I have not 
found any combination of BootX options that will produce serial output.

And I haven't been able to test the effect of config file changes to 
Debian's kernel because config-6.16.9+deb14-powerpc does not produce the 
kernel and modules that Debian distributes (the new vmlinux is over 200 
MB, modules are over 300 MB, bZimage is around 9 MB). I could start 
stipping out debugging and other features, but that would make the 
kernel quite different. Without being able to reproduce Debian's kernel, 
I'm stuck.

Using the attached config-6.17.5-pmac, which is a limited config file 
that includes only the options that are needed for most PowerPC G3 and 
earlier PowerPC PowerBooks, with no module support, everything works as 
expected, with both "video=ofonly" (check "No video driver" with no 
extra command line options), or the usual 
"video=atyfb:vmode:14,cmode:32,mclk:71" for my 1024x768 Wallstreet.

For your 800x600 Wallstreet, "video=atyfb:vmode:10,cmode:32" should 
work. It should also work to check "No video driver" in BootX with no 
extra command line options in BootX.

I'm using kernel 6.17.5 from www.kernel.org, but the latest mainline 
kernels also work.

-Stan