Make simple UEFI bootable ISO

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joevango
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Joined: Tue Apr 25, 2023 12:34 pm

Make simple UEFI bootable ISO

Post by joevango »

Greetings:

Given a UEFI application, lets call it 'grubaa64.efi', how can I make it into a UEFI bootable ISO file?

I tried grub-mukrescue but I don't want hundreds of megabytes of grub module files in my ISO, in theory, the only file needed in the bootable ISO file should be grubaa64.efi and perhaps some kind of boot catalog item?

I tried using PYCDLIB but can't figure out how to use it.
Octocontrabass
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Re: Make simple UEFI bootable ISO

Post by Octocontrabass »

joevango wrote:Given a UEFI application, lets call it 'grubaa64.efi', how can I make it into a UEFI bootable ISO file?
By "ISO" do you mean an optical disc image that will not work on any non-optical media?

Make a UEFI-bootable floppy disk (or hard disk) image, then instruct your optical disc image creation utility to use said image as the El Torito boot item for the EFI platform. The floppy/hard disk image may be pre-built, depending on where you got your copy of GRUB.
joevango wrote:I tried grub-mukrescue but I don't want hundreds of megabytes of grub module files in my ISO,
If grub-mkrescue is adding hundreds of megabytes of GRUB modules, something has gone wrong. It should be around ten megabytes at most, assuming you're targeting only a single architecture.
joevango wrote:in theory, the only file needed in the bootable ISO file should be grubaa64.efi and perhaps some kind of boot catalog item?
You also need bootaa64.efi and at least enough GRUB modules to load your OS.
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