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cancech
Asked: 2024-12-19 03:05:43 +0800 CST

Custom RHEL7 ISO UEFI USB installation failing to boot

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I have a custom RHEL7.8 installation ISO which works exactly as expected when I burn it to a DVD and install using that disk using UEFI. Now I am trying to update this to support installation from USB. I am able to generate an ISO and selected it as the boot device on my test system, however when I make my selection in the grub menu to trigger the installation I get an error:

error: file '/images/pxeboot/vmlinuz' not found.
error: you need to load the kernel first.

Press any key to continue...

What does this error mean and how do I fix this?

I have updated the /EFI/BOOT/grub.conf entry to reflect the media being USB rather than DVD

menuentry 'Option 1' --class fedora --class gnu-linux --class gnu --class os {
    linuxefi /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=MY_USB_LABEL quiet inst.ks=hd:LABEL=MY_USB_LABEL:/config/opt1/anaconda-ks-option1.cfg
    initrdefi /images/pxeboot/initrd.img
}

as well as copied the update grub.conf into images/efiboot.img.

mount images/efiboot.img /tmp/img
cp EFI/BOOT/grub.conf /tmp/img/EFI/BOOT/grub.conf
umount /tmp/img

The kickstart file is also updated to reflect the USB media (and I can use it successfully via Legacy Boot)

repo --name="USB Media" --baseurl=file:///mnt/install/repo # Added for USB install, not sure if necessary
install
harddrive --partition=LABEL=MY_USB_LABEL --dir=/ # in lieu of cdrom for DVD installation

I'm generating the ISO itself via mkisofs

mkisofs -quiet -o test.iso \
    -b isolinux/isolinux.bin \
    -J -R -l \
    -c isolinux/boot.cat \
    -no-emul-boot \
    -boot-load-size 4 \
    -boot-info-table \
    -eltorito-alt-boot \
    -e images/efiboot.img \
    -no-emul-boot \
    -graft-points \
    -joliet-long \
    -V MY_USB_LABEL iso_source/

isohybrid -uefi test.iso
implantisomd5 test.iso

and then "burn" it to the USB device

dd if=test.iso of=/dev/sda
sync

Thanks for any ideas, thoughts, or other feedback!

rhel7

1 Answers

  1. Best Answer

    Finally figured out what's going on... there's a search line in the grub.conf which also needs to be updated with the label of the drive. In a nutshell, for CD/DVD use this line isn't really necessary (it appears), meaning that when preparing this for DVD installation a few years back I assumed it was akin to the title that appears in isolinux.cfg. Consequently this this was written as:

    search --no-floppy --set=root -l 'Welcome to My Installation!'

    whereas in reality this is used to determine where the boot partition for the installer is and should read

    search --no-floppy --set=root -l 'MY_USB_LABEL'

    Not sure why it worked when installing from DVD, but I guess there's a "backup" mechanism to look for the boot partition on the DVD?

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