[CentOS] Custom ISO

Tue May 5 20:40:12 UTC 2020
Jerry Geis <jerry.geis at gmail.com>

Hi All,

I am trying to make a customer ISO. When I run this command:
mkisofs -o $DESTINATION_FILE -b isolinux/isolinux.bin -c boot.cat \
        -no-emul-boot -boot-info-table \
        -V "$NAME" -boot-load-size 4 -boot-info-table -R -J -v -T \
        -eltorito-alt-boot -e images/efiboot.img \

it tells me:
Size of boot image is 4 sectors -> No emulation
Size of boot image is 17408 sectors -> genisoimage: Error - boot image
'images/efiboot.img' has not an allowable size.

This is the exact same file that is on the Everything ISO image.

What am I missing ?  I also want to make the ISO boot with UEFI. I think I
have the right parameters but getting this error. Thoughts?