No replies to this topic

[steve6375]

The recent versions of Ubuntu and XUbuntu 24.04 ISO files do not contain a \boot\grub\i386-pc\core.img file but instead contain an eltorito.img file. Older versions used syslinux.

I am not asking about booting from an ISO file, but about booting from the files extracted from the ISO using grub4dos to run grub2 and load the grub2 menu system.

 

Previously I could use the kernel command in grub4dos to load the core.img file but this does not work with eltorito.img and I get a grub rescue prompt instead.

 

Perhaps because it is looking for a CD/DVD device?

 

Is there a way to copy the Ubuntu ISO file contents onto a FAT32 USB drive and then legacy boot those files from grub4dos?

I know we can use kernel and initrd, but this requires a bespoke menu to be created for each different ISO.

I infer that Rufus seems to need to download syslinux and add that to an Ubuntu ISO in order to make it legacy bootable...?

[Wonko the Sane]

I just did a couple experiments with https://ftp.gnu.org/...for-windows.zip

 

It seems that the difference in results between:

D:\GRUB2>grub-mkimage.exe -O i386-pc -o test.bin -p D:\grub2

and
D:\GRUB2>grub-mkimage.exe -O i386-pc-eltorito -o testel.bin -p D:\grub2

 

is that the latter is exactly the same as the second, bar an added whole CD sector (2048 bytes) at the beginning.

 

Maybe, just maybe, if you strip 2048 bytes from eltorito.img, it can be chainloaded.

 

The guy that used the U in GRUB for Unified has never been so wrong, welcome to GRUB, Grotesquely Repugnant Unfriendly Bootloader.

 

Wonko