docs: Document workaround for grub-mkrescue with older MacBooks

Add a description of the workaround for firmware of older MacBooks
which stalls with a grub-mkrescue ISO image for x86_64-efi target
on an USB stick.

Signed-off-by: Thomas Schmitt <scdbackup@gmx.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Thomas Schmitt 2019-06-20 10:36:42 +02:00 committed by Daniel Kiper
parent ff999c803e
commit f9811a92e6

View file

@ -6131,6 +6131,7 @@ Required files are:
@menu
* GRUB only offers a rescue shell::
* Firmware stalls instead of booting GRUB::
@end menu
@ -6201,6 +6202,17 @@ support has not yet been added to GRUB.
@end itemize
@node Firmware stalls instead of booting GRUB
@section Firmware stalls instead of booting GRUB
The EFI implementation of some older MacBook laptops stalls when it gets
presented a grub-mkrescue ISO image for x86_64-efi target on an USB stick.
Affected are models of year 2010 or earlier. Workaround is to zeroize the
bytes 446 to 461 of the EFI partition, where mformat has put a partition table
entry which claims partition start at block 0. This change will not hamper
bootability on other machines.
@node Invoking grub-install
@chapter Invoking grub-install