Chainloading from GRUB2 UEFI

[Apjue]

Hey there,

I'm using multibootusb to have one usb stick with multiple handy tools, and it fails to make a proper menuentry.
So I've inspected the memtest86 img file provided, and there are actually two img files contained in it. Am I supposed to use the one labelled "EFI System Partition"? I would also like to be able to boot in legacy mode. Although the other file has a "Legacy" note, it also contains a folder named EFI... So what should I do?

Thanks

[David (PassMark)]

We haven't attempted to do what you want to do and don't know the answer. Maybe someone in the community will.

Also, We don't support ISOs anymore. Using ISOs (which are only for CD/DVDs) to make USB drives is a sub-optimal process. We also don't know anything about multibootusb. It isn't our product.

[Apjue]

multibootusb basically just uses grub

Using ISOs (which are only for CD/DVDs) to make USB drives is a sub-optimal process.

Why? Is this true for any ISO or only for Memtest86?

[David (PassMark)]

The file system used by ISO, for CDs and DVDs doesn't work on a USB drive (or any hard drive). There is no good reason for this, but that's the way it is.
So to turn a bootable ISO into a bootable USB drive is a convoluted process with lots of permutations and file system conversion.
For USB drives it is easier to work directly with a copy of the USB drive, rather than convert to ISO and back.

[Oz (PassMark)]

In case anyone stumbles across this thread in the future and is interested in this process, we've recently written a guide on how to run MemTest86 directly from Grub.

Please see below link:

https://www.memtest86.com/tech_configuring-grub.html