Hello Gilles,
with this HACK you don't have to modify your kernel, initrd or
udeb-repository. Simply add this line to your preseed file:
d-i preseed/early_command string sed -i '/depmod -a > .dev.null 2>&1 ||
true/a modprobe ahci || true' /bin/hw-detect
It tries to modify /bin/hw-detect to unconditionally try to load the
ahci module after the "depmod -a"-command at the beginning of the
script. hw-detect is called (at least) 2 times before partitioning.
First for network-detect (at this time the sata-modules-udeb is
obviously not available and modprobe will fail) and a second time form
disk-detect. Now the sata-modules-udeb should have been installed
already and the ahci-module is ready to install - after "depmop -a" of
course.
This is no solution for the root cause of the problem.
To further investigate this it would be nice if you could confirm my
guess of a timing problem. For this you could add this line to your
preseed file (instead of the above of course):
d-i preseed/early_command string sed -i '/^update-dev >.dev.null$/i
sleep 10' /bin/hw-detect
or this:
d-i preseed/early_command string sed -i '/^update-dev >.dev.null$/i
udevadm control --reload' /bin/hw-detect
Hope this helps.
Jörg
