Re: PPC64

[Pavel Roskin]

Quoting Hollis Blanchard <address@hidden>:

> On Tue, 2008-10-21 at 18:04 -0400, Pavel Roskin wrote:
> > util/ieee1275/grub-install.in is not suitable for PowerPC.
>
> It worked great for me. :)

OK, I should have said that it's not suitable as a drop-in replacement  
for yaboot on PowerMACs.

> > It assumes that /boot is on the HFS boot partition.
>
> I documented the partitioning assumptions it uses:
> http://grub.enbug.org/TestingOnPowerPC

Actually, that page doesn't mention grub-install at all.  It suggests  
merging all modules with the core and installing it on the boot  
partition.

> > It's not the case for Fedora
> > and perhaps any distro.  The HFS boot partition is not mounted and
> > should be accessed by hfstools.  The modules should be installed
> > under /boot/grub.  The path to /boot/grub should be embedded into the
> > core image.  We have support for embedding the default module path now.
> > We need a better script that would not put all modules on the short HFS
> > boot partition.  Considering that the SPARC port is defunct, I would
> > just rewrite util/ieee1275/grub-install.in.
>
> The "boot partition" is an unnecessary hack instituted by a particularly
> opinionated ybin developer, and a great inconvenience. It's ridiculous
> to have scripts to copy and convert yaboot.conf files into a "secret"
> partition, especially since the bootloader is perfectly capable of
> discovering files at run time (unlike lilo, where the ybin model came
> from). Also, have you looked at those scripts? <shudder>

I don't quite understand what you mean here.  I don't care where  
yaboot looks for its configuration files.  I mean that GRUB should not  
rely on the kernel support for HFS and that the HFS boot partition  
should be used sparingly (it's a separate question whether yaboot does  
the best effort, but yaboot is small).

> On IBM POWER servers, there is no HFS partition at all. Instead, there
> is a "raw" partition onto which you dd an ELF file. Firmware loads the
> whole thing into memory and jumps at offset 0. Traditionally, yaboot is
> installed there, and when it runs it does a shoddy job of trying to walk
> the (DOS) partition table, searching for /etc/yaboot.conf.
>
> Once GRUB replaces yaboot/ybin we can happily wave both of these
> anachronisms goodbye. Firmware on both systems is fully capable of
> loading ELF files from a filesystem, and since it's on a filesystem
> there is no need to embed anything or search anywhere: all files
> (grub.cfg and the modules) should be placed adjacent to the executable.

Actually, I would prefer all files that don't have to be on HFS or on  
the raw partition to be on the native partition, so that they can be  
easily accessed.  That includes grub.cfg.

> As for embedding the path in the executable itself, that's a nice idea
> until you copy the executable to another system or move your hard disk
> to another system where devices have different Open Firmware paths and
> aliases. Another big pain point is building bootable CDs, since these
> also unfortunately cannot make assumptions about the Open Firmware
> devices available.

We can use UUIDs now.  That should alleviate most issues.

> Just put all the files in the same directory on a real filesystem and be
> happy. I know I am. :)

I'm afraid I'm missing something.

Anyway, I think it's too much to ask from users to change the existing  
partitioning or mount points.  GRUB can be more compatible with both  
its i386 implementation and with yaboot by keeping modules in  
/boot/grub on ext2 or another native filesystem and placing the  
minimal core to the machine specific boot partition (whether it's HFS  
or raw or something else).

The goal of my previous message was to list the issues I ran into.   
Inability to use grub-install as is was one of them, and it has not  
been addressed.

--
Regards,
Pavel Roskin