From 56157556b6f0892169d5bee18aa0ee88fa07a379 Mon Sep 17 00:00:00 2001 From: Thomas Schmitt Date: Thu, 20 Jun 2019 10:36:42 +0200 Subject: [PATCH] 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 Reviewed-by: Daniel Kiper --- docs/grub.texi | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/docs/grub.texi b/docs/grub.texi index 1127c86f0..54b0e17ae 100644 --- a/docs/grub.texi +++ b/docs/grub.texi @@ -6200,6 +6200,7 @@ Required files are: @menu * GRUB only offers a rescue shell:: +* Firmware stalls instead of booting GRUB:: @end menu @@ -6270,6 +6271,17 @@ 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