When using mkisofs to create a bootable image, must all required files be placed in the same directory?

Support
1 
mkisofs -V "BOOTISO" -A "FirPE Boot ISO" -U -max-iso9660-filenames -D -R -J -joliet-long -hide-joliet boot.catalog -no-emul-boot -boot-load-size 4 -b grldr -eltorito-alt-boot -no-emul-boot -eltorito-platform efi -eltorito-boot efiboot.img -o ~/e
fiboot.iso .

I don’t want to put the boot file grldr and efiboot.img into the generated iso9660 file system.
mkisofs: Uh oh, I cant find the boot image '../grldr' inside the target tree.

In fact, it is not necessary to put these two files in the iso9660 file system. I deleted these two files using ultraiso under Windows, and my ISO image can still be started.

Is there any way to bypass this restriction?

Or other tools?

2

… just parsing your command line … and checking against the mkisofs manual page man mkisofs:

-U
    Allows "Untranslated" filenames, completely violating the iso9660 standards described above. Forces on the -d, -l, -N, -allow-leading-dots, -relaxed-filenames, -allow-lowercase, -allow-multidot and -no-iso-translate flags. It allows more than one '.' character in the filename, as well as mixed case filenames. This is useful on HP-UX system, where the built-in CDFS filesystem does not recognize ANY extensions. Use with extreme caution.

-D
    Do not use deep directory relocation, and instead just pack them in the way we see them.
    If ISO9660:1999 has not been selected, this violates the ISO9660 standard, but it happens to work on many systems. Use with caution.

-joliet-long
    Allow Joliet filenames to be up to 103 Unicode characters. This breaks the Joliet specification - but appears to work. Use with caution. ...

-boot-load-size load_sectors
    Specifies the number of "virtual" (512-byte) sectors to load in no-emulation mode. The default is to load the entire boot file. Some BIOSes may have problems if this is not a multiple of 4.

you specified “4” - perhaps omit that and use the default?

-no-emul-boot

is used two times in your command

-b grldr

you gave it on the command line, but you removed it from your source (is what I understood)
… omit this option, so it won’t look for that non existing file? …

no actual advise :man_shrugging: