[bug #63784] grub-mkconfig generates invalid code that passes grub-script-check when / is ZFS and there is no initrd

[Arsen Arsenović]

URL:
  <https://savannah.gnu.org/bugs/?63784>

                 Summary: grub-mkconfig generates invalid code that passes
grub-script-check when / is ZFS and there is no initrd
                 Project: GNU GRUB
               Submitter: arsen
               Submitted: Fri 10 Feb 2023 09:33:49 PM CET
                Category: Configuration
                Severity: Major
                Priority: 5 - Normal
              Item Group: Software Error
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 2.02~rc1
                 Release: 
         Discussion Lock: Any
         Reproducibility: Every Time
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: Fri 10 Feb 2023 09:33:49 PM CET By: Arsen Arsenović <arsen>
Note: I'm actually on 2.06.  This release isn't listed on the submit page,
though.

If / is ZFS and there's no initrd, a rather peculiar sequences of failures
happens.
Let's suppose the following:


~$ GRUB_DEVICE="`grub-probe --target device /`"
~$ echo "$GRUB_DEVICE"  # Note the newline.  This becomes problematic later.
/dev/nvme0n1p1
/dev/sda1
~$ grub-probe --device $GRUB_DEVICE --target=fs
grub-probe: warning: disk does not exist, so falling back to partition device
/dev/nvme0n1p1.
grub-probe: warning: disk does not exist, so falling back to partition device
/dev/sda1.
grub-probe: warning: disk does not exist, so falling back to partition device
/dev/nvme0n1p1.
grub-probe: warning: disk does not exist, so falling back to partition device
/dev/nvme0n1p1.
grub-probe: warning: disk does not exist, so falling back to partition device
/dev/sda1.
grub-probe: warning: disk does not exist, so falling back to partition device
/dev/sda1.
grub-probe: error: disk `hostdisk//dev/nvme0n1p1' not found.
~ 1 $ # The above results in a GRUB_FS=unknown, replaced by zfs.


Later, in 10_linux, the following block replaces the root device with
"$GRUB_DEVICE" from above:


  if test -z "${initramfs}" && test -z "${initrd_real}" ; then
    # "UUID=" and "ZFS=" magic is parsed by initrd or initramfs.  Since
there's
    # no initrd or builtin initramfs, it can't work here.
    if [ "x${GRUB_DEVICE_PARTUUID}" = "x" ] \
        || [ "x${GRUB_DISABLE_LINUX_PARTUUID}" = "xtrue" ]; then

        linux_root_device_thisversion=${GRUB_DEVICE}
    else
        linux_root_device_thisversion=PARTUUID=${GRUB_DEVICE_PARTUUID}
    fi
  fi


This results in the following menuentry:


        menuentry 'Gentoo GNU/Linux, with Linux 6.1.8-gentoo-dist' --class 
gentoo
--class gnu-linux --class gnu --class os $menuentry_id_option
'gnulinux-6.1.8-gentoo-dist-advanced-/dev/nvme0n1p1_/dev/sda1' {
                load_video
                set gfxpayload=keep
                insmod gzio
                insmod part_gpt
                insmod ext2
                set root='hd1,gpt2'
                if [ x$feature_platform_search_hint = xy ]; then
                 search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2
--hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2 
2b360390-ecee-4481-8e15-5d440e562863
                else
                 search --no-floppy --fs-uuid --set=root
2b360390-ecee-4481-8e15-5d440e562863
                fi
                echo    'Loading Linux 6.1.8-gentoo-dist ...'
                linux   /vmlinuz-6.1.8-gentoo-dist root=/dev/nvme0n1p1
        /dev/sda1 ro console=tty12 splash quiet 
        }


In general, 10_linux (and presumably others) seem unprepared for odd
GRUB_DEVICE values.

I'm unsure what a correct, or even decent, fix here is.. perhaps failing when
GRUB_DEVICE is determined to be more than one device?  While that is, of
course, an error while running mkconfig, it's presumably better to an
unbootable system.
In that case, the user could specify their root device manually, maybe?

Thanks in advance, have a lovely day.







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