I've found the culprit. This bugs still occurs for me, and its not grub's fault.
On powerpc machines, the bootloader (grub2 along with yaboot) are put on a separate partition, which is HFS formatted.
I mount this partition as /boot/grub.
The problem is with hfsutils: even if they report (e.g. via the output of "mount") that this filesystem is mounted read-write, after an abrupt halting of the machine it's mounted read-only. The only real fix is to manually unmount /boot/grub, run fsck on it which clears the dirty flag, and then remounting it and running grub2 installation again.
So I believe that fixing the output of mount, or forcing a fsck when mounting a hfs volume, is the only real solution to this.
Or whenever the filesystem gets dirty, and update-grub is called, you'll get errors, potentially leaving your system unusable.
I've found the culprit. This bugs still occurs for me, and its not grub's fault.
On powerpc machines, the bootloader (grub2 along with yaboot) are put on a separate partition, which is HFS formatted.
I mount this partition as /boot/grub.
The problem is with hfsutils: even if they report (e.g. via the output of "mount") that this filesystem is mounted read-write, after an abrupt halting of the machine it's mounted read-only. The only real fix is to manually unmount /boot/grub, run fsck on it which clears the dirty flag, and then remounting it and running grub2 installation again.
So I believe that fixing the output of mount, or forcing a fsck when mounting a hfs volume, is the only real solution to this.
Or whenever the filesystem gets dirty, and update-grub is called, you'll get errors, potentially leaving your system unusable.