Bug#801237: mactel-boot review
Hi,
(still being subscribed on debian-mentors to learn customs)
Christian Kastner wrote:
> That article seems to contain some misinformation. For example:
> | So why is the system unbootable? The problem is that the Mac
> | bootloader expects the EFI partition to be formatted as HFS+, the
> | typical Mac filesystem.
> I have a MacBook Air (2013), and the EFI system partition came formatted
> as FAT.
Because my program xorriso serves as producer of bootable ISOs,
i can tell that GRUB2 program grub-mkrescue under some
configuration circumstances wants HFS+ tree and metadata, marked
by an Apple Partition Map and blessed by whatever makes holy.
It gets this from xorriso mainly by HFS+ code contributed by
Vladimir Serbinenko.
The Fedora LiveCD ISO has a small HFS+ image file, also marked
by APM. The HFS+ image gets made as disk data file by some tools.
The ISO is made by genisoimage. MBR, GPT, and APM are patched in
by program "isohybrid" from SYSLINUX.
Debian amd64 and i386 installation ISOs still have a (useless)
APM left over from the setup described in
http://mjg59.dreamwidth.org/11285.html
"Anatomy of a Fedora 17 ISO Image".
That APM marks no HFS+ but only a FAT. (Made by xorriso.)
So Matthew Garrett and Vladimir Serbinenko know Macs which need HFS+
and some which do not. Steve McIntyre seems not to have had contact
with owners of the HFS+ addicts. (Me neither. I just write bytes
on amd64 hardware.)
Debian powerpc ISOs have HFS metadata without "+" and are made by
genisoimage. I am not aware whether these boot on some other,
probably even older Macs.
I understand that older Macs make few difference between HDD and CD
when it comes to booting. APM or nothing.
Newer UEFI compliant machines have to look for El Torito on CD,
and for MBR partitions or GPT on HDD. But the partition content
is in both cases the same.
Have a nice day :)
Thomas
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