Re: Debug grub scripts without rebooting into grub shell.

[Hongyi Zhao]

On Sat, Jul 8, 2023 at 9:53 PM Andrei Borzenkov <arvidjaar@gmail.com> wrote:
>
> On 08.07.2023 14:58, Hongyi Zhao wrote:
> > Hi here,
> >
> > Are there some convenient methods to debug grub scripts without
> > rebooting into grub shell?
> >
>
> You may try grub-emu which emulates grub.

I tried, but it seems that grub-emu doesn't meet my requirement as
described below.

I want to debug the grubx64.efi created by the following command:

$ grub-mkstandalone -O x86_64-efi -o grubx64.efi --modules='lvm fat
ntfs part_msdos part_gpt ext2 btrfs probe regexp search configfile'
boot/grub/grub.cfg=./grub.cfg

The content of the ./grub.cfg is as follows:

$ egrep -v '^[ ]*(#|$)' grub.cfg
regexp -s __cmdpath_efi '^\(([^,]+)' "$cmdpath"
export __cmdpath_efi
for file in ($__cmdpath_efi,*)/multibootusb.git/grub.cfg; do
  if regexp -s __root '^(\([^*]+\))' "$file"; then
    set __prefix=$__root/multibootusb.git
    export __root
    export __prefix
    configfile $__prefix/grub.cfg
    break
  fi
done

The files' layout is as follows:

$ tree .
.
├── grub.cfg
├── grub-mkstandalone.sh
├── grubx64.efi
└── iso
    ├── deepin-desktop-community-23-Beta-amd64.iso
    ├── rescatux-0.74.iso
    ├── supergrub2-2.06s1-beta2-multiarch-CD.iso
    ├── systemrescue-10.01-amd64.iso
    ├── ubuntu-23.04-desktop-amd64.iso
    └── ubuntukylin-23.04-desktop-amd64.iso

1 directory, 9 files

Regards,
Zhao