Re: GRUB_CMDLINE_LINUX="... memmap=8G$8G"

[Andrei Borzenkov]

On 22.12.2023 07:23, John Groves wrote:
> Thanks for the reply Randy!
>
> No luck so far, but here is what I tried:

I cannot reproduce it on the openSUSE Leap 15.5.

> COMMON="BOOT_IMAGE=(hd0,gpt2)/vmlinuz-6.5.12+ root=/dev/mapper/fedora-root
> ro rd.lvm.lv=fedora/root"
>
> Test 1:
>      /etc/default/grub:
>      GRUB_CMDLINE_LINUX="rd.lvm.lv=fedora/root memmap=8G!8G"
>
>      journalctl -k:
>      Command line: $COMMON memmap=8G!8G
>
> Test 2: (double quotes and un-escaped '$')
>      /etc/default/grub:
>      GRUB_CMDLINE_LINUX="rd.lvm.lv=fedora/root memmap=8G$8G"


$8 will be expanded by grub-mkconfig to the (most likely) empty value

>      journalctl -k:
>      Command line: $COMMON memmap=8GG
>
> Test 3: (single-quotes and un-escaped '$')
>      /etc/default/grub:
>      GRUB_CMDLINE_LINUX='rd.lvm.lv=fedora/root memmap=8G$8G'

$8 will be expanded by grub CLI when processing menu entry and results 
in 8GG here

>      journallctl -k:
>      Command line: $COMMON memmap=8G
>
> Test 4: (single quotes and escaped '$')
>      /etc/default/grub:
>      GRUB_CMDLINE_LINUX='rd.lvm.lv=fedora/root memmap=8G\$8G'

This works and results in 8G$8G in /proc/cmdline

>      journalctl -k:
>      Command line: $COMMON memmap=8G
>
> Test 5: (single quotes and double-escaped '$')
>      /etc/default/grub:
>      GRUB_CMDLINE_LINUX='rd.lvm.lv=fedora/root memmap=8G\\\$8G'

This results in passing 8G\\$8G on kernel command line.

>      journalctl -k:
>      System panicked during boot. See attached screen grab image
> [image: Screenshot 2023-12-21 at 10.20.37 PM.png]
>
> An further suggestions?

Finally show generate grub.cfg lines.