Re: macbook EFI experiences

[Isaac Dupree <id@isaac.cedarswampstudios.org>]

Robert Millan wrote:
> On Fri, May 30, 2008 at 05:01:51PM -0400, Isaac Dupree wrote:
>>> You don't need to use the header of one of your partitions.  You can use
>>> the MBR or even have a dedicated partition for core.img.  Then you can 
>>> install
>>> the rest of GRUB in a filesystem that's not case unsensitive! ;-P
>> I know, but I don't entirely understand how it works and I'd rather 
>> not... and it gives me limited options: theoretical maximum of 5 I 
>> think, 1 in MBR and 1 in each of first four partitions (each with their 
>> own hacks).
> 
> You're confusing BIOS-based boot with msdos partition labels.  You can use
> GPT just fine when booting from BIOS (although Intel tries to hide that
> fact by embedding the GPT spec inside the EFI spec).

I have the hack which combines the two partition labels so I have both 
GPT and msdos labels.  Which means that my first four partitions (only) 
are listed in msdos, and GPT is the really accurate one that MacOS and 
Linux use.  However, I can't find a way to get into bootloader-land via 
BIOS without going through the msdos partitioning mechanism.

>> I much prefer being able to put as many .efi files as fit 
>> all on one partition, for refit to find.  As it is, when I upgrade GRUB, 
>> there always has to be the fear that I did something wrong that I can't 
>> easily fix because it's not just in the location of my files (it's 
>> hidden in mbr/partition headers), and because I can't boot into Linux 
>> anymore because I broke the bootloader :-)  It's been very lucky that I 
>> can so far always boot into OS X without going through GRUB, and edit my 
>> grub.cfg from there... That, and keeping 10.4 updated, are the two main 
>> reasons I ever boot into MacOS :-)
> 
> I think what we need here is to support MacOS boot from GRUB.  Then you
> can use GRUB as your bootloader and don't need to use it as a piece of
> glue between Refit and Linux..
> 
> Want to help us on that? :-)

that'd be nice... although I kind of like it how it is for me now, 
choosing Mac vs. GRUB in rEFIt, so I'm not *particularly* inspired to 
help :-)

>>> Btw what's a CSM?
>> "Compatibility Support Modules", it's a name for the BIOS substitute 
>> that Apple added to EFI to support their "Boot Camp"/Windows.
> 
> Notice that, like "EFI", "BIOS" doesn't imply any underliing implementation;
> it just defines an interface (Intel uses this confusion to pretend their
> firmware is free, when in fact only its shell -EFI- is).  Unless I missed
> something, Apple's BIOS is as much a BIOS as is any other one.

I think you're right about that.  (Except that I don't think that even 
the EFI part of the firmware is free on Apple computers, as far as I 
know they've done proprietary modifications to the free 
example-implementation and not been interested in releasing firmware 
sources.)

-Isaac