Shim doesn't respond to boot parameters

[GBember01]

I'm trying to boot my gentoo system with shim. My boot entry is
Boot0003* Gentoo via Shim HD(1,GPT,c12a7328-f81f-11d2-ba4b-00a0c93ec93b,0x800,0x200000)/File(\EFI\gentoo\shimx64.efi)bzImage.efi and I also tried \EFI\gentoo\bzImage.efi instead of just bzImage.efi, but despite that, it only tries to load the grub executable, which doesn't exist on my system. I'm following the Gentoo wiki and it states for systemd-boot efibootmgr --disk /dev/sda --part 1 --create --label "Systemd-boot via Shim" --loader '\EFI\systemd\shimx64.efi' --unicode '\EFI\systemd\systemd-bootx64.efi', I'm doing the same, just for my kernel

[christoph-at-unicon]

@amilton78 What hardware? Did you enable verbosity (mokutil --set-verbosity true) to learn more about what shim tries to boot?

[dennis-tseng99]

it only tries to load the grub executable, which doesn't exist on my system.

If you trace shim.c code, you will find that shim will automatically load grub:

efi_main()
{
    ...
    init_grub(image_handle);
    ....
}

Hope not to misunderstand your problem.

[alexojegu]

@Amilton78, do you have a Dell board? So it may be related to this: #698

[GBember01]

@Amilton78 What hardware? Did you enable verbosity (mokutil --set-verbosity true) to learn more about what shim tries to boot?

I haven't tried that yet. I'll see what it outputs
Edit: Seems like it only tries to load grubx64

[GBember01]

it only tries to load the grub executable, which doesn't exist on my system.

If you trace shim.c code, you will find that shim will automatically load grub:

efi_main()
{
    ...
    init_grub(image_handle);
    ....
}

Hope not to misunderstand your problem.

I thought you could specify which binary to boot based on boot parameters

[GBember01]

@Amilton78, do you have a Dell board? So it may be related to this: #698

I'm using an Asus AMD board, B550

[alexojegu]

If you want to try, #698 (comment) worked for me.

[pudgyunicorn]

If you want to try, #698 (comment) worked for me.

Per the suggesting from @alexojegu , #698 indeed worked for me. @Amilton78 , you may need to add a terminating character to the unicode argument string. Something like:

--unicode '\EFI\systemd\systemd-bootx64.efi \0'

Edit: To add, I am on a ThinkPad T480. So, not a Dell board. I don't think the board necessarily matters; it's more of a c thing.

[GBember01]

@pudgyunicorn I'll try that tomorrow, I'm not on a dell board either, but hopefully this works. Thanks!

[GBember01]

@pudgyunicorn sorry for the wait. It actually worked! Should I close this issue now?

[tenzap]

If you want to try, #698 (comment) worked for me.

Per the suggesting from @alexojegu , #698 indeed worked for me. @Amilton78 , you may need to add a terminating character to the unicode argument string. Something like:

--unicode '\EFI\systemd\systemd-bootx64.efi \0'

Edit: To add, I am on a ThinkPad T480. So, not a Dell board. I don't think the board necessarily matters; it's more of a c thing.

I found that for me (with an ASUS motherboard), using --unicode '\EFI\systemd\systemd-bootx64.efi \0' as you suggest actually results in having the \0 as text in the boot option (my shell is bash). Of course, it works with this argument, but the \0 is not required. If I just keep the trailing space (using --unicode '\EFI\systemd\systemd-bootx64.efi '), it works as well and is not confusing by letting believe that \0 would translate into the NUL character.

To really have a terminating NUL character in UCS-2, you would have to use the command suggested in #698 (comment) .

To check whether you have a terminating NUL, do this way:

1. find the bootnum entry of the corresponding entry with efibootmgr -v (it is referred to as below)
2. find the guid-name of the efi var with efivar -l | grep <BootXYZT>
3. get the hexdump of the entry with efivar -p -n <guid-name>

An alternative to #698 (comment), that actually does the conversion to UTF2 slightly differently, would be:

printf '%s\0' "\EFI\Systemd\systemd-bootx64.efi" | iconv -t ucs2 | \
	efibootmgr --create -d /dev/sda -p 1 \
		-L 'Linux Boot Manager' \
		-l '\EFI\Systemd\shimx64.efi' \
		-@ -

Here the conversion to ucs2 is done with iconv, instead of sed.

I also found that the absolute path to the efi (\EFI\Systemd\systemd-bootx64.efi in this example) is not required if it is in the same directory as shimx64.efi. Incoking printf '%s\0' "systemd-bootx64.efi" | iconv -t ucs2 | \... would actually be sufficient.

The comments of the parse_load_options in https://github.com/rhboot/shim/blob/15.8/load-options.c#L306 gives an idea of what is expected.