Re: Trouble making bootable USB from ISO image
- Date: Sat, 04 May 2019 11:41:33 +0200
- From: "Thomas Schmitt" <scdbackup@xxxxxxx>
- Subject: Re: Trouble making bootable USB from ISO image
> I was trying to setup UEFI bootable USB. All worked fine
> until grub told me something I do not recall exactly at the moment, but
> answers I found were pointing to the fact that you can not do grub
> update/install of UEFI if you are not booted into UEFI.
This is plausible together with Nicolas George's statement:
> > To edit UEFI variables, the computer need to have booted in UEFI mode.
But as said, the hack only tries to lure EFI into considering the block
range 2060 to 10365499 as (alternative) System Partition. It is a mere
partition table operation, no installation of a boot loader.
The loader and subsequent system are already prepared in the EFI partition
and the ISO. After EFI did its work of starting program \EFI\BOOT\BOOTX64.EFI
it depends on them whether they can deal with being on a not intended storage
medium. (The initrd of Debian ISOs has shell code which finds out the device
where the ISO is stored.)
The individual EFI firmware which shall act on the USB stick is actually
not determined when the ISO gets prepared. So there is no occasion or desire
to set non-volatile variables before the ISO gets booted.
Have a nice day :)