Volume 2
CSM-BIOS boot notes:
Apple hardware tested:
mbp41 = MacBookPro 4,1 (2008), Nvidia Geforce8600M GT.
mbp82 = MacBookPro 8,2 (2011), Intel HD Graphics 3000 and AMD Radeon HD 6750M.
All notes based on booting with the Apple-EFI option-key startup menu to choose
how to boot, not rEFIt.
1. After default install using any installation type, and reboot, neither model
loads GRUB2 (and thus does not boot) by default. Pre or post-install work is
needed.
2. Both models CAN boot and startup Fedora to a GUI login with pre- or
post-install work.
a. 'nogpt' kernel parameter for Fedora only installs produces a
bootable system without post-install work.
b. In dual-boot (Mac OS + Fedora) anaconda isn't creating a hybrid MBR
post-install, therefore Apple's EFI startup disk menu doesn't see the F16
installation. Further, creating the hybrid MBR in advance is useless as parted
wipes out the hybrid MBR in favor of a protective MBR just prior to
installation. (See 3 below for additional fallout of this behavior.)
c. Triple boot (Mac OS, Fedora, Windows) is possible, but there are
more ways this won't work, than will work. And more ways that will work, but
aren't good partition schemes (invitations for data loss) since there really
isn't such a thing as a safe hybrid MBR + GPT. I have found one or two that I
think are about as "safe" as they can get, and it means that the user needs to
install Mac OS, Windows, Fedora, in that order, but located on the disk in
order: Mac OS, Fedora, Windows.
3. Anaconda + parted consistently remove pre-existing hybrid MBRs, replacing
them with protective MBRs. The hybrid MBR will exist in a case where Windows
has already been installed (using Apple's Bootcamp application). If removed in
favor of a protective MBR, Windows is no longer bootable. So not only is Fedora
not bootable, a previously bootable Windows is no longer bootable. This happens
with either EFI or BIOS mode installs of Fedora.
So either anaconda needs to proceed no further upon discovery of a hybrid MBR,
or it needs to become pretty good at sorting out hybrid MBR and GPT schemes
that are "safe".
4. gptsycnc: I don't think gptsync has such a sophisticated heuristic for
creating such hybrid MBRs - I regularly see it produce very linear MBRs while
suggesting huge percentages of the disk are empty. Any MBR only aware tool
would see these areas as fair game - what I call an invitation for data loss
and probably not a good idea.
5. If all requirements are met, Apple's startup disk menu (option-key at
startup chime) will present a single "Windows" disk icon which if selected will
load GRUB2 and its menu. That "Windows" label is apparently hard coded in
Apple's EFI for any foreign OS requiring legacy CSM-BIOS booting.
Additional EFI boot notes:
1. By default EFI//EFI/redhat/grub.efi isn't found by Apple's EFI and install a
choosable option. If it and the .conf are moved to EFI//EFI/BOOT/BOOTX64.efi
and .conf, both models have an "EFI Boot" labeled disk icon in the option-key
startup menu. I'm guessing like the "Windows" equivalent, that "EFI Boot" is
hardwired.
This is being addressed by this:
https://bugzilla.redhat.com/show_bug.cgi?id=755093
2. GRUB-EFI (legacy) regularly just hangs are loading the kernel and initramfs,
on mbp41. I don't have this problem with GRUB2-EFI but I still have other
problems mentioned in the previous email.
Chris Murphy--
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