Use PBR with BIOS Boot Partition, not blocklists?

[Isaac Dupree]

Hi GRUB-ers,


BACKGROUND:

Apple's BIOS implementation, at least on my Macbook2,1 , flips out and 
fails to boot if you put GRUB* in the usual MBR location.**  The only 
way I've found to boot from disk in BIOS mode is to have a hybrid 
GPT/MBR partition table*** with one partition marked MBR-bootable and 
with grub installed in that partition's Partition Boot Record (PBR).

My layout:

partition 1: BIOS Boot Partition
partition 2: FAT16 (marked as "Microsoft basic data" ****)
partition 3: Linux swap
partition 4: main Linux partition

(That's all; it's Linux-only.)


PROBLEM:

When I tried installing GRUB to the MBR (`grub2-install /dev/sda`), grub 
found and used the BIOS Boot Partition automatically (so far, so good). 
 But when installing GRUB to the FAT16's PBR (first use gptfdisk to 
create a hybrid MBR with partition 2 marked bootable, then 
`grub2-install /dev/sda2`), GRUB demanded to use blocklists, even though 
there was a perfectly usable BIOS Boot Partition nearby.  I reluctantly 
forced it to use blocklists so I could boot Linux from disk at all, but 
does GRUB provide an alternative?  Is there any way to tell GRUB to use 
one partition's PBR and another partition as core.img space?  I can mark 
it as something other than "BIOS Boot Partition" in GPT if I'd be 
abusing that marking's semantics.

Hmm, I just realized I didn't try `grub2-install /dev/sda1`.  Would that 
work to use the BIOS Boot Partition to contain both the 
four-hundred-odd-byte boot record as well as the core.img?  If so, I'll 
go pick up my boot-CDs and partition tools again, do that, and (either 
way) document it all in a blog post.

Or other ideas?

Thanks!

-Isaac


* tested with GRUB 1.98 because that's the latest that System-Rescue-CD 
provided and it was good enough. (*sad*)

** the Arch Linux wiki suggests others observe this problem too. ( 
https://wiki.archlinux.org/index.php/MacBook "Also in the install boot 
loader stage, install GRUB on whatever partition that /boot is on. 
Warning: Do not install GRUB onto /dev/sda !!! Doing so is likely to 
lead to an unstable post-environment." )

*** or maybe pure MBR, but Intel Macs are biased enough towards GPT that 
I see no reason to bother testing whether it works.  GPT is a nice 
partition scheme anyway.

**** There are reasons for these choices; ask and/or I'll blog.