On Sat, 2 Jan 2016 10:06:54 +0100
Didier Kryn <kryn@???> wrote:

> Le 02/01/2016 03:44, Stephanie Daugherty a écrit :
> > Regardless of who proposed it, merged /usr is still a reckless
> > change > that needlessly complicates things.
>
>

>      Hey Stephanie.

>

>      The simple fact of splitting executables between two different 
> directories *is* a complication; merging them back would be a 
> *simplification* :-). 

The preceding is true. It's obviously simpler to put all the
distro-installed executables in one directory. However...

The Unix community has a long tradition of splitting the one-tree
filesystem into mounted partitions, and there are several excellent
reasons to have /usr on its own partition. Once /usr is on its own
partition, /usr/bin, /usr/sbin, and /usr/lib are unavailable without
mounting, and where are the executables needed to mount them? Oops!

But there's a solution: Initramfs! Cool! Except that initramfs is one
or two more orders of magnitude more complicated than executable
splitting. So the slight simplification of merging directories buys you
a huge complication of initramfs black-boxism.

And one thing Stephanie said keeps ringing in my ears: Until very
recently, you could take it to the bank that you could
substitute /bin/bash in your grub line, and come up to a working OS,
where you could look around, and see what it takes to mount things and
get everything running, and craft your rc file. But now you come up in
some purgatory where you have to learn a whole nother file hierarchy
before manually doing your switch_root or pivot_boot, and only then can
you use /bin/bash the way she suggested. And take it from me, on Ubuntu
that's a long, long road.

> I've read, from a guy who followed the story,
> that it was originally split because the first disk was too small.

Not really. He mounted a second volume becuase the first disk was too
small. He split executables to accommodate mounted volumes. We still
have mounted volumes, and so far nobody's talking about getting rid of
them. So we still very much have the same reasons to split executables.
Or substitute a huge black box initramfs for executable splitting.


DISCLAIMER...

I pick my battles. I'll fight to the death to keep systemd away from my
PID1. I'd fight hard to minimize or eliminate all systemd software from
my box because once the camel gets his nose in the tent, the next thing
you know the whole camel's sleeping next to you. It would be wonderful
to have a no-systemd udev, so the Poetterists don't have a single point
of failure they can invoke at will on my system, but so far the
systemd-encumbered udev still works with normal systems. Hey, if I had
all my druthers, there'd be no dbus on my system.

In the hierarchy described in the preceding paragraph, re-splitting the
executables fits in somewhere between no-systemd udev and no dbus. It
would be nice, but I could easily live without it.

So why am I involved in this discussion at all? Because there's a
debate over whether the merge aids the Poetterists, and there's no
doubt about that in my mind: It does.

And like Stephanie said several posts back, it sure was nice to set
your grub command to /bin/sh, and come up in a working (though not
fully mounted) operating system.

SteveT

Steve Litt
January 2016 featured book: Twenty Eight Tales of Troubleshooting
http://www.troubleshooters.com/28