On 18/12/2023 at 08:55, Andrei Borzenkov wrote:
You can also probably load a 32 bit kernel from a 64 bit grub.
Why would you would want to do this ? A 32-bit kernel cannot read or
write 64-bit EFI variables.
We are back to the same question - what are criteria for
choosing the "right" kernel that grub needs to implement?
(...)
Besides, distributions may require additional CPU features beyond mere
"supports 64 bit".
Do you mean 32-bit CPU features such as PAE ?
https://en.wikipedia.org/wiki/X86-64#Microarchitecture_levels
Debian provides only a single kernel flavour for the amd64 architecture,
and two flavours for i386: 686 (without PAE) and 686-pae. So this script
should do the trick:
if [ $grub_cpu = x86_64 ]; then
set arch=amd64
elif [ $grub_cpu = i386 ]; then
if cpuid -l ; then
set arch=amd64
elif cpuid -p ; then
set arch=686-pae
else
set arch=686
fi
elif [ $grub_cpu = arm64 ]; then
set arch=arm64
elif [ $grub_cpu = riscv64 ]; then
set arch=riscv64
fi
