Re: clang appends an extra string to Grub2 making it not work with MBR s

From:

Vladimir 'phcoder' Serbinenko

Subject:

Re: clang appends an extra string to Grub2 making it not work with MBR systems

Date:

Thu, 12 Jan 2023 16:13:40 +0300

Can you upload diskboot.exec and boot.exec somewhere? Did you see any errors? Ideally we should have errored out if those files are not 512 bytes

On Tue, 3 Jan 2023 at 09:09, Immolo via Grub-devel <grub-devel@gnu.org> wrote:

Using Gentoo with clang on a MBR system I have come across an extra string the content /lib/ld-linux.so.2 is being added to /usr/lib/grub/i386-pc/diskboot.img and /usr/lib/grub/i386-pc/boot.img taking it over 512 bytes meaning it can't be used on a MBR system.

You can use truncate to remove the extra string then it will install and boot correctly but I am highlighting this here in hopes of a better fix.

Steps to reproduce in Gentoo:

Use a clang stage3 on a MBR system.
emerge -va sys-boot/grub
grub-install /dev/sda

Error:

Installing for i386-pc platform.
grub-install: error: diskboot.img size must be 512 bytes.

Workaround:
1. truncate -s 512 /usr/lib/grub/i386-pc/diskboot.img
2. truncate -s 512 /usr/lib/grub/i386-pc/boot.img
3. grub-install /dev/sda
I'm not really sure what files I can attach to help debugging this one but if you can think of any please ask for them.
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Regards
Vladimir 'phcoder' Serbinenko