On Sunday 11 March 2012 21:08:47 Robin H. Johnson wrote:
> On Sun, Mar 11, 2012 at 12:49:11AM -0600, Ryan Hill wrote:
> > On Sat, 10 Mar 2012 20:27:06 -0600
> > 
> > William Hubbs <williamh@g.o> wrote:
> > > An initramfs which does this is created by >=sys-kernel/genkernel-3.4.25
> > > or
> > > 
> > > >=sys-kernel/dracut-017-r1. If you do not want to use these tools, be
> > > 
> > > sure any initramfs you create pre-mounts /usr.
> > 
> > We should really have some documentation on how to create a minimal
> > initramfs that mounts /usr (if we don't already, I haven't looked).  I've
> > never needed one until now and don't have the foggiest idea how it's
> > done.  I can't be the only one.
> 
> The quickest initramfs, assuming that ALL kernel modules you need to
> boot are already compiled into your kernel:
> genkernel --install --no-ramdisk-modules initramfs

But this will not mount /usr. At least it did not for me.
To make it work you have to 

# echo "/usr" >> /etc/initramfs.mounts

and recreate the ramdisk (genkernel ramdisk)

I had to look into the code for that as this seems not to be documented 
anywhere.

-Marc