Re: [Qemu-ppc] Booting Lubuntu 16.04 on qemu-system-ppc produces errors

[BALATON Zoltan]

Hello,

On Tue, 9 Jul 2019, Andrew Randrianasulu wrote:
> First my 32-bit qemu from git build was just segfaulting, then I tried simpler 
> iso (finnix) and found at least
> one error while booting to console:
>
> ./ppc-softmmu/qemu-system-ppc -M mac99,via=pmu -L ./pc-bios -cdrom 
> ~/finnix-ppc-110.iso -m 512  -display sdl,gl=on   -d guest_errors,unimp -boot d
> invalid/unsupported opcode: 3f - 0e - 1a - 00 (fc200e9c) 204a73f0 1

finnix-ppc-111.iso boots for me but I get different invalid/unsupported 
opcode error:

invalid/unsupported opcode: 1f - 0c - 1a - 00 (7c000e99) 6fe429d0 1

> Next, I tried similar line  but with G3 processor forced:
>
> ./ppc-softmmu/qemu-system-ppc -M mac99,via=pmu -L ../queue-vga/pc-bios -cdrom 
> /mnt/sdb1/PPC-img/lubuntu-16.04-desktop-powerpc.iso -m 512  -display sdl,gl=on  
> -device ati-vga,guest_hwcursor=true  -d guest_errors,unimp -boot d -cpu G3
> invalid/unsupported opcode: 04 - 02 - 12 - 00 (10000484) 0fcf10f0 1
> invalid/unsupported opcode: 04 - 02 - 12 - 00 (10000484) 1ffaf0f0 1
> invalid/unsupported opcode: 04 - 02 - 12 - 00 (10000484) 204470f0 1
> invalid/unsupported opcode: 04 - 02 - 12 - 00 (10000484) 0f95e0f0 1
> invalid/unsupported opcode: 04 - 02 - 12 - 00 (10000484) 0f95e0f0 1

There's no need to force G3, seems to work the same with the default G4 
and boots for me (albeit very slowly and sometimes complaining about 
some missed irq) again giving error about same opcode as above:

invalid/unsupported opcode: 1f - 0c - 1a - 00 (7c000e99) 0fcf1110 1
invalid/unsupported opcode: 1f - 0c - 1a - 00 (7c000e99) 20590110 1
invalid/unsupported opcode: 1f - 0c - 1a - 00 (7c000e99) 20272110 1
invalid/unsupported opcode: 1f - 0c - 1a - 00 (7c000e99) 0f95e110 1
invalid/unsupported opcode: 1f - 0c - 1a - 00 (7c000e99) 0f95e110 1

I'm not sure what this is supposed to be, I could not identify what 
instruction this could be and why it's considered invalid. (Or if it's 
really invalid why does it appear in guest code.) But regardless seems to 
boot so maybe this is something the guest code has to be compatible with 
more processors and these are handled by guest.

> this booted up to (corrupted colors, but this was using fbdev X driver) LXde 
> desktop.

The corrupted colors are because some mismatch with frame buffer 
endianness. This iso uses 15 bpp mode. Reverting commit a38127414 
(ati-vga: Fix frame buffer endianness for big endian target) fixes this 
but that breaks MorphOS Rage128 driver so one of these is probably wrong 
(and Linux, or OpenBIOS if it uses open firmware console is more likely to 
be wrong here). Or maybe they access the frame buffer differently as the 
card has support for big-endian aperture which may not be emulated 
correctly yet. I think this should be checked on a real PowerMac3,1 to see 
which of these isos actually work on real hardware to make sure we're 
testing with correct guest code.

Regards,
BALATON Zoltan