fedora 15 use a the ram disk / file system initialization image to load custom linux driver modules
old fedora (up to fedora13) it used the standard "initrd-***.img" for such purpose
ans mkinitrd tool can create and modify such image file
But from fedora 14 it uses "initramfs***.img" file containing the driver images
and the tool which can create and modify it is "dracut"
to view the driver embedded in "initramfs***.img" the following command can be used
lsinitrd /boot/initramfs-....img > /home/.../initramfs.txt
to add new driver in the image use the following command (--force will over write the existing image in /boot)
*** make a backup of the original before using the following command ***
dracut /boot/initramfs-....img --force --add-drivers xhci-hcd
Make sure all kernel firmware are present or installed your system
if not the new image will not be created
for kernel updation and automatically include the custom driver edit the following line in file "/etc/dracut.conf"
# additional kernel modules to the default
#add_drivers+="xhci-hcd"
to
# additional kernel modules to the default
add_drivers+="xhci-hcd" #remove the '#' at beginning
################################################## ####################################
Now the /boot partition should be in internal bootable HDD which the MBR should refer with all the vmlinuz and initramfs image
'/' (main or root) partition can be in kept in USB-3.0 HDD connected through NEC chipset PCI express card which is seemed to be not bootable directly
Here is some typical boot entry for grub
title Fedora (2.6.38.8-32.fc15.x86_64)
root (hd0,2) # referring the /boot partition
# root=/dev/sdb7 refers the external "/" or root partition
kernel /vmlinuz-2.6.38.8-32.fc15.x86_64 ro root=/dev/sdb7 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb quiet
initrd /initramfs-2.6.38.8-32.fc15.x86_64.img