Kernel not recognized as bootable UEFI binary

[Juesto]

Luet version:

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CPU architecture, OS, and Version:

x86_64
Describe the bug

Unable to boot live iso in uefi due to firmware being unable to recognize the kernel as a uefi executable
To Reproduce

1. put iso in usb
2. boot into uefi shell
3. try to let it boot via startup.nsh

Expected behavior

being able to boot in uefi mode
Logs

Additional context

trying with MocaccinoOS-XFCE-0.20230707.iso.tar.xz from 1.3 github release
the only uefi related file is startup.nsh containing commands to launch the kernel
I've attempted to run the kernel manually from the shell without success either
the use of startup.nsh is usually reserved for efi shells and such, most systems recognize bootable .efi files
Rufus only offers mbr/bios for the partition table meaning it does not detect uefi in the iso

[joostruis]

As we talked about on the telegram chan. This happens with older firmware that is unable to handle EFI stub.

[mudler]

To me it looks like we have CONFIG_EFI_STUB enabled: https://github.com/mocaccinoOS/desktop/blob/62ad7c54bec8b01ed86d93d34d3cc44498fd9744/packages/kernels/kernels/mocaccino/kernel/mocaccino-x86_64.config#L466, @Juesto can you provide a bit more context? what is the hw specs here? can you reproduce with modern HW?

[Juesto]

not all systems support direct kernel uefi boot, and most systems dont support startup.nsh at all @mudler

just efi stub does not make the iso efi compliant, providing efi shims will make this more compatible and compliant