Re: BIOS/GPT with bios_gub raw partition: core image is too big

[Pascal Hambourg]

Le 19/02/2021 à 15:33, moo can via Support requests for the GRand 
Unified Bootloader a écrit :
> Hello,
> I need to install grub2 on a x86_64 computer with BIOS and GPT partition 
> table.If I understand well in BIOS/GPT, the bios_gub raw partition is here to 
> host/handle the core.img (not writed in mbr).

Correct.

> So I made a bios_gub raw partition big enough to host the core.img:
Number    Start (sector)   End (sector)    Size        Code      flags
1           2048            12287         5.0MiB       EF02    bios_gub

5 MiB for a BIOS boot partition is much more than enough. Even 1 MiB is 
more than enough.

> When I use grub-mkstandalone to generate the core.img
> grub-mkstandalone -O i386-pc -o core.img --modules= ....
>
> I have : core image is too big (0x185161 > 0x78000)
> Is it possible to "bypass" this size limitation or is it hardcoded in i386-pc 
> format even if the grub_bios raw partition exist ?

I do not think that the BIOS boot partition size is relevant to 
grub-mkstandalone. Check 
<https://www.gnu.org/software/grub/manual/grub/grub.html#Core-image-size-limitation>
I guess that somehow the core image must fit within the ~640 KB x86 real 
mode memory.
But why do you want to use grub-mkstandalone instead of grub-install ?