Re: Is there a way to get the architecture of the machine just booted up by GRUB2: [32|64]-[amd|arm]? ...

[Pascal Hambourg]

On 17/12/2023 at 12:08, Albretch Mueller wrote:
>   Say I burn a DVD with the debian bootable iso (the live DVD) for
> amd64, arm64 and 64-bit risc-v processors

Debian does not provide any such multi-arch ISO image. Until bookworm it 
provided a amd64+i386 multi-arch image which was able to boot with PC 
BIOS (with ISOLinux, 32-bit x86 UEFI and 64-bit x86 UEFI (with GRUB).

> will GRUB2 automatically
> detect the architecture and pick the file?

Let's assume you you create such an ISO image for UEFI boot only. It 
must contain an EFI partition with EFI images for each firmware 
architecture : bootarm64.efi (built for ARM64), bootx64.efi (built for 
AMD64/x86_64) and bootriscv64.efi (built for RISC-V64). The UEFI 
firmware will seek the matching EFI image, and the GRUB image will 
report the architecture in $grub_cpu and $grub_platform.

Note: bootxxx.efi may be a GRUB image or a shim image which loads 
grubxxx.efi in turn (for secure boot).