Hi, thank you for flying xorriso.
I have two objections towards the commit message, code comments, and the list in cdmakerpkg: xorriso does not use mkisofs. It can emulate parts of the mkisofs command line interface by help of its own code and its associated libraries. grub-mkrescue of GRUB2 indeed depends on xorriso and mtools. But mkisofs is not involved with grub-mkrescue since about 10 years. Have a nice day :) Thomas