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To: gentoo-dev@g.o
From: Joost Roeleveld <joost@...>
Subject: Re: udev and /usr
Date: Thu, 15 Sep 2011 22:40:19 +0200
On Thursday, September 15, 2011 02:29:20 PM Rich Freeman wrote:
> On Thu, Sep 15, 2011 at 11:07 AM, Zac Medico <zmedico@g.o> wrote:
> > On 09/15/2011 07:33 AM, Joost Roeleveld wrote:
> > > The use for an initrd/initramfs/... will create an additional layer
> > > of
> > > complexity a lot of us users are not really waiting for, especially
> > > as we> 
> > are
> > 
> > > not seeing any issues with our current systems.
> > 
> > Like it or not, it's the simplest possible solution if you want separate
> > /usr. The plan is to provide a minimal initramfs that won't contain any
> > modules, so it won't have to be rebuilt for each kernel. See the "/usr
> > vs. initramfs redux" thread:
> It should be noted that the alternative is to use a more full-featured
> initramfs like dracut, which will also be updated to support mounting /usr
> (it already parses /etc/fstab to remount root anyway).
> The minimal initramfs will not contain mdadm or lvm tools, so it is
> basically suitable for booting systems that don't currently require an
> initramfs.  Of course, something like dracut is more likely to require you
> to rebuild the initramfs every time you update your kernel, and won't simply
> be a static image like the simplified one.
> The simplified initramfs could be compiled into the kernel as Zac suggests
> (this is probably the most foolproof method), or it could be loaded from
> /boot using the appropriate grub settings.

Is there an option in Grub to add a "default" initramfs that is used for all 
boot-options that can be overriden per boot-set?

In other words, if I don't specify an initramfs for a kernel, that this 
default is then automatically applied?
And will this then also work when using Xen where the kernel is already passed 
as a module?

> Note that dracut does drop you to a shell if it fails (this is
> configurable), but by default this shell is dash, not bash.  No doubt it
> would work fine either way, but bash is likely to be a little slower.  I
> don't think RAM use is likely to be a problem - it should be completely
> de-allocated before init runs.

It is my understanding all the options need to be specified every time dracut 
is run to create an initramfs. If this becomes mandatory, will this be added 
to the "make" script of the kernel-sources and as such, make this more 

Another issue arrises where some of the tools are updated that are also in the 
initramfs. Will we then still need to remember to also update the initramfs if 
these are needed?

My server currently uses mdadm raid1 for /, /boot and swap and raid1+lvm for 
the rest. This works without the need of an initramfs.

Will this still work? Or will I need to be using dracut instead?

Please note, I'm not the only one using this option as it was taking directly 
from the Gentoo guides:


Re: udev and /usr
-- Rich Freeman
udev and /usr
-- Joost Roeleveld
Re: udev and /usr
-- Zac Medico
Re: udev and /usr
-- Rich Freeman
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Updated Jun 29, 2012

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