400d needs the bootflags, not only the card bootable...
this is the main reason i'm interested in .fir files... so far we (in 400plus) are using one testfir.fir which will enable the bootflags, but it is hanging the camera after doing it... so i though it would be nice to have our firmware (autoexec.bin) running by firtmware update (w/o flashing it to the ROM actually), and i can make a new menu to enable the bootflags from there ...
this way, everyone can test the firmware and if he/she likes it, can enable the bootflags and put the autoexec.bin to the CF card.
from what i see in the bootloader, the routine which enables the booflags will write the volume label to the CF too...
from the information you gave me, i see that i need to learn more about the structures of the .fir files...
thanks.