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Re: Debian Installer GRUB test image available

On 06/05/2019 10:35, John Paul Adrian Glaubitz wrote:

> On 5/5/19 4:24 PM, Mark Cave-Ayland wrote:
>> Right, these graft points are unnecessary - if you look at the BootX file on the ISO
>> then it's simply a pointer to /boot/grub/powerpc-ieee1275/grub.chrp which is a
>> bootinfo file containing this:
>> boot &device;:&partition;,\System\Library\CoreServices\grub.elf
>> and from above this is simply a link to /boot/grub/powerpc.elf, which is also
>> different to the bootinfo file that already exists at \ppc\bootinfo.txt which would
>> be picked up by CHRP machines by default. It feels like we're just going around in
>> circles.
> So everyone who has been creating bootable PowerPC ISOs for Debian stable releases
> and GRUB has been doing it all wrong? I have a hard time believing that. Given the
> fact that the OpenFirmware implementation in PowerMacs seems to be non-standard which
> we can also see with grub-ofpathname not printing proper OpenFirmware paths, I tend
> to believe it's better to follow the common practice for creating these images.

It's difficult to say because the Debian images you've created are the first ones I
have that use grub unless you have pointers to any others? But certainly across all
the OS images I use to test boot QEMU/OpenBIOS none of them reference the above path
at all.

> Referencing specs doesn't convince me really because specs don't necessarily
> mean that the firmware properly implements them. If WINE developers implemented
> the Win32 API according to spec, the compatibility of WINE for real world applications
> would be much worse.

I agree with your point here, all I'm pointing out is the above path has no existing
precedent for Linux bootable CDROMs so please don't consider it to be an existing
convention or standard.

>> To summarise again:
>> - Mac machines locate the TBXI filetype in the blessed directory
>> - CHRP machines as defined by the specification look at \ppc\bootinfo.txt
>> I really can't see why we can't just bless \ppc, set the \ppc\bootinfo.txt file type
>> to TBXI and then both Mac and CHRP work with only one copy of each file instead of
>> having all these aliases and graftpoints?
> Because Apple's OpenFirmware is not 100% compliant with the spec and I would rather
> have images that work on every PowerMac than something that is valid according to
> a specification that no user really cares about in the end.

Oh I know - OpenBIOS has to replicate some of these bugs in order to be able to boot
certain ISOs :)  However all the bugs I've come across so far have been related to
tree iteration and property retrieval, the first stage boot tends to always "just work".



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