Recreating NetInstall ISO doesn't work

[mhavu]

I'm trying to create a bootable USB flash drive for kickstart installation based on CentOS-7-x86_64-NetInstall-1810.iso. However, something seems to be wrong with the way I'm creating the image. As soon as I select the boot option (or after initrd ready message), the computer reboots. If I write the unmodified ISO to the flash drive, it works:

Code: Select all

sudo dd if=CentOS-7-x86_64-NetInstall-1810.iso of=/dev/sda

However, if I extract the the files and recreate the ISO, I get the instant reboot behaviour:

Code: Select all

file-roller -e iso CentOS-7-x86_64-NetInstall-1810.iso
mkisofs -o custom.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -V 'CentOS 7 x86_64' -r -J iso
isohybrid custom.iso
sudo dd if=custom.iso of=/dev/sda

I have tried also options -R and -T in mkisofs, but they seem to make no difference.

Any ideas what might be wrong here? I may have problems in the kickstart file or isolinux.cfg, but before I get there, I should at least be able to boot the repackaged ISO.

Edit: I had left out the isohybrid command from the listing.