Re: [RFC] libexecdir

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Jun 20 11:17, Christopher Faylor wrote:
> On Thu, Jun 20, 2013 at 05:10:57PM +0200, Corinna Vinschen wrote:
> >On Jun 20 10:19, Christopher Faylor wrote:
> >> On Thu, Jun 20, 2013 at 10:20:51AM +0200, Corinna Vinschen wrote:
> >> >Conflicts like this will happen.  If we change libexec, we have to be
> >> >prepared for this kind of stuff.  Is it worth it?
> >> 
> >> I certainly have gone through this "pain" when the changeover was made
> >> on Linux.  If we want to provide the real Linux look-and-feel I don't
> >> think we have any choice.  :-)
> >> 
> >> But, seriously, I think that the change makes sense in the long run. If
> >> we don't do this we'll eventually just have to be tweaking more and more
> >> configurations to put things in /usr/libexec rather than /usr/lib.
> >
> >Yeah, probably.  Me and my lawn...
> 
> I see you got what I meant even though I got the sense wrong.
> 
> >> On a similar note, what about Fedora (and others) fusion of /usr/bin <> /bin
> >> and /usr/sbin <> /sbin?  Do we want to think about that too?  It would
> >> certainly make sense for Cygwin.  We could get rid of /usr/bin entirely.
> >
> >No, we can't.  Fedora has /usr/bin, /usr/lib and /usr/sbin, while the
> >/bin, /lib, and /sbin paths are just symlinks to their /usr counterparts.
> >This is necessary to maintain hardcode paths, and this will not go away
> >in Fedora for a long time.
> 
> I guess I should have checked before sending the email but my point was
> if we should be eschewing the use of whichever Fedora has gotten rid of.
> You're right that /bin is a symlink.  So should cygport and others now
> be forcing everything into /usr/whatever?

By default prefix is /usr anyway when building packages with cygport.  I
don't see a reason to disable packages from specifing /bin as installation
path.  After all, it's dumped into the same place anyway.

> >For Cygwin we did this fusion anyway since version 1.1 or so, just as
> >mount points and in the other direction.  We were far ahead of time :)
> >
> >Having said that, we could do the same for /sbin vs. /usr/sbin and
> >create an automatic mount point for it as well.
> 
> Although I think they were my idea, I have never really liked the
> automatic mount points.  Couldn't we just use a symlink?

I'm not really loving them either, but the original reason to have
/usr/bin and /usr/lib mount points rather than symlinks is performance.
That was already the case in pre-1.7 Cygwin when we had the automatic
generation of the /usr/bin and /usr/lib mount points in the registry.

Handling mount points is noticably faster than handling symlinks.
Symlinks require to read file content and since /usr/bin is first in
$PATH by default, you get lots and lots of open/read/close calls on the
/usr/bin symlink.  Even if the file is cached, it's probably still
slower than just fetching the mount point from the internal mount table.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat