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Re: New discussion: ppc64 installer -- ext2 /boot partition to keep sabot happy.

On 10/01/2017 11:00 AM, Rick Thomas wrote:> 1) I did a test installation with manual partitioning using the 20170927 installer (Debian GNU/Linux 9.0 _Sid_ - Unofficial ppc64 NETINST 20170925-19:46). I created a 10MB bootstrap HFS partition and a 250MB /boot ext2 partition. It had no problem installing yaboot to the 10MB HFS partition, and no trouble booting from it using that yaboot. So we can say that it is possible to use an HFS partition as large as that with yaboot. Whether it works with grub2 is a question for another day.

I recently stumbled upon [1] which mentions an "8M" limit (either 8 MB or 8 MiB) for the PReP partition which holds the stage1 binary - most likely yaboot or grub - for IBM POWER machines.

[1]: https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/W51a7ffcf4dfd_4b40_9d82_446ebc23c550/page/PowerLinux%20Boot%20howto

This is also reflected in the current partman recipes for "powerpc-chrp_ibm" and "powerpc-prep" (and respective ppc64 targets) on [2]:


8 1 1 prep
	$primary{ }
	$bootable{ }
	method{ prep } .

So maybe 8 MB/MiB as maximum size for the PReP partition could also be a good candidate for the size of the HFS partition on Apple powerpc and ppc64 machines.

"8 MB/MiB ought to be enough for anybody", don't you agree? ;-)

[2]: https://anonscm.debian.org/cgit/d-i/partman-auto.git/tree/

As mentioned before, I don't know how to mount this PReP partition on my POWER5 machine. I assumed there is a VFAT FS on this partition, but mounting it as VFAT doesn't succeed. So maybe there's no FS at all on this partition but just a stage1 binary. Maybe it's dd'ed directly to this partition - if someone could shed some light on this, I'd be grateful. :-)

One other thought:

It could also be that the size of the partition is not an issue for the firmware, but the size of the stage1 binary could be. The original 800 KB limit on Power Macs could be also to make sure, that the stage1 binary cannot be bigger than 800 KiB, which was the same size as a Mac 3.5" floppy disk according to Rogério Brito on [3].

[3]: http://cynic.cc/blog/posts/running_grub2_on_powerpc_macs/


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