separate /usr/broken with udev extras

separate /usr/broken with udev extras

[William Hubbs]

All,

Wehave the following bug report on gentoo linux regarding udev and and
external dependencies on a system with a separate /usr partition.

http://bugs.gentoo.org/show_bug.cgi?id64235

Comment #1, in particular, is of interest to me, because I think we
could solve this on gentoo if we had event types that told us when these
failures happened. Right now, it seems that all ofthese failures are
marked nomatch by udev, could they be marked as failed instead?

Thanks,

William

failures occurred or 

Re: separate /usr/broken with udev extras

[Kay Sievers]

On Sat, Jul 30, 2011 at 22:40, William Hubbs <w.d.hubbs@gmail.com> wrote:
> Wehave the following bug report on gentoo linux regarding udev and and
> external dependencies on a system with a separate /usr partition.
>
> http://bugs.gentoo.org/show_bug.cgi?id64235
>
> Comment #1, in particular, is of interest to me, because I think we
> could solve this on gentoo if we had event types that told us when these
> failures happened. Right now, it seems that all ofthese failures are
> marked nomatch by udev, could they be marked as failed instead?

Udev does not support missing tools which are referenced from rules,
that's just an error that is logged.

Today we can not expect a successful bootup with /usr empty and 'half'
of the needed tools missing. Most of the basic stuff, including udev
itself has usually nothing in /usr, but the number of tools needing
things from /usr is growing all the time, and it's unrealistic to
fix/change them all. Too many tools do not support to be started with
an empty /usr, and it's not as simple a fixing udev to re-run the
events.

Please mount /usr from initramfs before 'init' is started, or if the
setup is simple enough, at least before udev and other services start.

We just gave up supporting the split of tools in / vs. /usr. It does
not make much sense today anymore, all tools should be available
during bootup.

Related to this, you might want to read:
  http://www.freedesktop.org/wiki/Software/systemd/separate-usr-is-broken

Kay

Re: separate /usr/broken with udev extras

[Marco d'Itri]

On Jul 30, Kay Sievers <kay.sievers@vrfy.org> wrote:

> We just gave up supporting the split of tools in / vs. /usr. It does
You did, as shown many times other distributions surely did not.

I don't even know /how/ I could stop supporting a standalone /usr: some
distributions actually support upgrading a system to the next release,
and this cannot require repartitioning.

-- 
ciao,
Marco

Re: separate /usr/broken with udev extras

[Kay Sievers]

On Sat, Jul 30, 2011 at 23:23, Marco d'Itri <md@linux.it> wrote:
> On Jul 30, Kay Sievers <kay.sievers@vrfy.org> wrote:
>
>> We just gave up supporting the split of tools in / vs. /usr. It does
> You did, as shown many times other distributions surely did not.

Good luck!
I'm looking forward to things like patches for the D-Bus config moving
to the rootfs. :)

> I don't even know /how/ I could stop supporting a standalone /usr: some
> distributions actually support upgrading a system to the next release,
> and this cannot require repartitioning.

Some stuff is broken for years for all non-simple services. The real
fix is just a cp -ax away, I guess. :)

As mentioned, the distro's fix is to mount /usr from initramfs, and
that's the only realistic option for /{bin,lib} vs. /usr/{bin.lib}
split, with the ever-growing use of tools from /usr during bootup.

The random split of tools tools in /{bin,lib} vs. /usr/{bin.lib} makes
no sense today, what /{bin,lib} was for UNIX is the initramfs for
Linux today.

We are actually currently planning to move all tools from the rootfs
to /usr, where they belong and sort out the chaotic split of install
locations. There will be only compat symlinks left in / then.

Kay

Re: separate /usr/broken with udev extras

[William Hubbs]

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On Sat, Jul 30, 2011 at 11:23:00PM +0200, Marco d'Itri wrote:
> On Jul 30, Kay Sievers <kay.sievers@vrfy.org> wrote:
> 
> > We just gave up supporting the split of tools in / vs. /usr. It does
> You did, as shown many times other distributions surely did not.
> 
> I don't even know /how/ I could stop supporting a standalone /usr: some
> distributions actually support upgrading a system to the next release,
> and this cannot require repartitioning.

Right, I have had a separate /usr on all of my installed systems for
years, and I don't know of a reason having this shouldn't be supported.

I would rather see us work on fixing the tools so that it can still be
done.

William


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Re: separate /usr/broken with udev extras

[Kay Sievers]

On Sat, Jul 30, 2011 at 23:53, William Hubbs <w.d.hubbs@gmail.com> wrote:
> On Sat, Jul 30, 2011 at 11:23:00PM +0200, Marco d'Itri wrote:
>> On Jul 30, Kay Sievers <kay.sievers@vrfy.org> wrote:
>>
>> > We just gave up supporting the split of tools in / vs. /usr. It does
>> You did, as shown many times other distributions surely did not.
>>
>> I don't even know /how/ I could stop supporting a standalone /usr: some
>> distributions actually support upgrading a system to the next release,
>> and this cannot require repartitioning.
>
> Right, I have had a separate /usr on all of my installed systems for
> years, and I don't know of a reason having this shouldn't be supported.

Claiming as a distro that booting up with and empty /usr, with 'half'
of the tools missing, is just wishful thinking, and it the end not
more than a lie. In reality It works reliably only for limited
requirements regarding device config. I see all these bugs for many
years now.

> I would rather see us work on fixing the tools so that it can still be
> done.

Honestly, I don't think that will ever happen. It's just too much
stuff to fix and change.

Very basic server-like setups will just continue to work as they did
before. But more and more of the new stuff will just fail in
non-interesting ways.

All things that expect the new stuff to run properly, need to get an
initramfs that can mount /usr before init is started, or need to copy
/usr back to the rootfs. There is no other realistic option, really.

Kay

Re: separate /usr/broken with udev extras

[William Hubbs]

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On Sat, Jul 30, 2011 at 11:45:39PM +0200, Kay Sievers wrote:
> Some stuff is broken for years for all non-simple services. The real
> fix is just a cp -ax away, I guess. :)
> 
> As mentioned, the distro's fix is to mount /usr from initramfs, and
> that's the only realistic option for /{bin,lib} vs. /usr/{bin.lib}
> split, with the ever-growing use of tools from /usr during bootup.
> 
> The random split of tools tools in /{bin,lib} vs. /usr/{bin.lib} makes
> no sense today, what /{bin,lib} was for UNIX is the initramfs for
> Linux today.
> 
> We are actually currently planning to move all tools from the rootfs
> to /usr, where they belong and sort out the chaotic split of install
> locations. There will be only compat symlinks left in / then.

Why not go the other way and move things that udev needs from /usr to /?

That would be an easier transition imho than moving everything to /usr.

William

> 
> Kay
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Re: separate /usr/broken with udev extras

[Kay Sievers]

On Sun, Jul 31, 2011 at 00:14, William Hubbs <w.d.hubbs@gmail.com> wrote:
> On Sat, Jul 30, 2011 at 11:45:39PM +0200, Kay Sievers wrote:
>> Some stuff is broken for years for all non-simple services. The real
>> fix is just a cp -ax away, I guess. :)
>>
>> As mentioned, the distro's fix is to mount /usr from initramfs, and
>> that's the only realistic option for /{bin,lib} vs. /usr/{bin.lib}
>> split, with the ever-growing use of tools from /usr during bootup.
>>
>> The random split of tools tools in /{bin,lib} vs. /usr/{bin.lib} makes
>> no sense today, what /{bin,lib} was for UNIX is the initramfs for
>> Linux today.
>>
>> We are actually currently planning to move all tools from the rootfs
>> to /usr, where they belong and sort out the chaotic split of install
>> locations. There will be only compat symlinks left in / then.
>
> Why not go the other way and move things that udev needs from /usr to /?
>
> That would be an easier transition imho than moving everything to /usr.

Because many of these tools have dependencies on libs in /usr, or
config in /usr/share. It's a game we can not win realistically, we
will need to move too much stuff to /, which makes the entire idea of
splitting / and /usr in the first place moot.

What's not needed today is stuff in /. We can think of /usr a /System.
The entire system is installed in one single directory, and that can
be mounted r/o, or even shared between many hosts/guest. The stuff on
the rootfs is always host-only then.

Kay