[CentOS] Centos6: Boot from usb 3.0ls /

Peter Kjellström

cap at nsc.liu.se
Thu Mar 1 08:44:12 UTC 2012


On Wednesday 29 February 2012 06.07.03 John Doe wrote:
> From: Volker Poplawski <volker at openbios.org>
> 
> > The required xhci_hcd kernel module is not part of the 260 modules in
> > the initrd for some reason. Sony Memory-Stick is included, if you happen
> > to have one of these...
> > I was able to rebuild the initrd plus the xhci_hdc module:
> > mkinitrd -v --with=xhci_hdc
> > /boot/initramfs-2.6.32-220.4.2.el6.x86_64.img `uname -r`
> > Now, how do I tell centos to add the module everytime a new kernel is
> > installed/updated?
> 
> Isn't mkinitrd looking at /etc/modprobe.conf?
> Or is it only limited to fs, ide/scsi and raid modules?

Let me try to unconfuse this situation:

1) CentOS-6 does not use initramfstools, mkinitrd is just a thin shell wrapper 
on top of dracut

2) dracut by default adds lots of drivers to the initramfs (not only what's 
needed, that is, -H is not the default)

3) dracut does not include *hci_hcd modules since ehci, uhci and ohci are 
built in, not compiled as modules (this could be considered a bug...).

4) you spelled the driver wrong above, it's xhci_hcd not hdc

To conclude, to build a new initramfs for the current kernel with dracut:

dracut --add-drivers xhci_hcd /boot/initramfs-$(uname -r).img $(uname -r)

To make it permanent look at the add_drivers line in /etc/dracut.conf or add a 
/etc/dracut.conf.d/...

/Peter
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