Re: [gentoo-user] Re: After /usr conflation: why not copy booting software to /sbin rather than initramfs?

[Alan Mackenzie]

On Wed, Mar 28, 2012 at 12:55:20AM +0200, Alan McKinnon wrote:
> > On Tue, Mar 27, 2012 at 11:48:19PM +0200, Alan McKinnon wrote:
> > > On Tue, 27 Mar 2012 21:24:22 +0000
> > > Alan Mackenzie <acm@×××.de> wrote:

> > > > That is precisely what the question was NOT about.  The idea was
> > > > to copy (not move) booting software to /sbin instead of an
> > > > initramfs - the exact same programs, modulo noise - to have the
> > > > SW in /sbin necessary to mount /usr.

> > > Two words:

> > > shared libraries

> > > Copying binaries is not enough. You have to find and copy every
> > > shared library those binaries use. Plus all the data and other
> > > files they might need.

> > > This is non-trivial.

> > <silently screams>.  It's equally non-trivial for initramfs, yet
> > nobody seems to be raising this objection for that.

> > Why is nobody else on this thread willing to take up its main point,
> > the exact equivalence between the known, ugly, initramfs solution and
> > the as yet half-baked idea of putting the same binaries into /sbin?


> Read my other mail and pay attention to the difference between
> transient and persistent.

In my proposed solution, the executables in /sbin would only exist until
/usr had been mounted and the runtime PATH set up.  After the unification
of /usr, /sbin won't even exist (apart from in schemes like mine).

> initramfs is an elegant engineering solution (albeit over-engineered
> for our specific case of being Gentoo users).

Maybe, maybe not.  It couples the various bits of booting more tighly
together.  I look at Allan Gottlieb's bug "WARNING latest lvm2 breaks
systems with older udev", and note that he recovered, essentially, by
mounting non-/ partitions by hand and going back to an old lvm2 version.
I had a similar problem when I was first trying out Walter's mdev
solution, which I also recovered by mounting by hand.

I look forward with foreboding to the time when such recovery will not be
possible.  Only a legacy Gentoo system or a recovery CD will help then.
I think it highly probable that "can't boot" bugs will continue to happen
occasionally.  I'd like to carry on having a bootable skeleton system for
when this happens.

> Your questions are about an extremely ill-advised action that has no
> sound basis. It copies stuff around to make one very specific thing
> work but with zero consideration for what it will do to everything
> else. That is bad, bad engineering.

I don't think that's a fair summary.

> If you want all this stuff in /, then do it correctly and modify the
> ebuilds to put the originals there (and troubleshoot the fallout from
> other faulty hard-coded stuffs). This is a lot of work, but it is sound.

I doubt that would work, for the reasons you give.

I feel I've been needlessly slammed, all for articulating an interesting
idea.

> --
> Alan McKinnnon
> alan.mckinnon@×××××.com

-- 
Alan Mackenzie (Nuremberg, Germany).