Multiboot ELF Loader - Alignment

[Chris Plant]

Hello,

I'm continuing to play with Multiboot2 on ARM64 on a Raspberry Pi, and
I've run into something which I'm trying to understand.

I have an ELF file for my kernel which has two segments (I have no idea
why rust is giving me two segments, but it is).  If I boot directly
into the ELF file from the Pi firmware it boots fine, but if I boot via
GRUB I have issues with data corruption in .rodata which is in the
second segment.  The first segment (.text) appears to load correctly.

Digging into this, the ELF headers specify a load base address of
0x801060 for the second segment, but GRUB allocates and loads this to
0x802000.  If I change my linker to align the second segment onto
0x1000 everything works fine.

Is this alignment to 0x1000 a defined behaviour of the GRUB allocator
or Multiboot2?  I'm assuming it's not a problem with the ELF file as
it's generated by usual means and runs fine otherwise.

Thanks,

Chris