> uh...  so, install them early on in the boot sequence.

I've a similar scenario (albeit on an ISA card): I'm including "microcode
bootstrap code" in the kernel image (less than 1 kByte). This code is
downloaded and bootstrapped at probe time. It does the real hardware probe,
as I'm not able to do that outside the device and delivers an OK or FAILURE
response to the probe (with some more hardware information, but that doesn't
matter in this context) and (as a side effect) drops into "ready to receive
real code once" mode and  waits for a userland utility (run early in
bootstrap) to dump a file into it.

Once this happened, it starts up this downloaded image and will never be able
to receive another download again (besides the device being hardware-reset
by the driver).


Martin