How to boot on iso file from USB boot to hdd iso file

[luddeycy]

Hi all,

i just started to try using gentoo...
i usually, with others distro, boot on a USB stick...and continue the boot process on a "iso file" available on hdd...

in the loader options

with debian, i used :
boot=live live-media=/dev/disk/by-label/blah live-media-path=/the/path/where/iso/is

with slackware, i used :
livemedia=/dev/disk/by-label/blah:/the/path/where/iso/is/ISO_FILE.iso

with fedora, i used :
root=live:LABEL=blah rd.live.image rd.live.dir=/the/path/where/iso/is/LiveOS

with manjaro, i used :
img_dev=/dev/disk/by-uuid/1234ABCDblahblah img_loop=/the/path/where/iso/is/ISO_FILE.iso


but with gentoo iso file, transfered in this HDD, i didn't find the way to do same thing...
root=LABEL....
root=live:....

could you please help me find the "right" cmdline options to be able to boot with iso file on HDD ?

NOTE : the system boot is currently refind, but not sur it's important....i need to know the cmdline ?


THANKS in advance.

David