Re: /usr/lib vs /usr/libexec
On Tuesday 10 May 2005 02:18, Goswin von Brederlow
<brederlo@informatik.uni-tuebingen.de> wrote:
> Russell Coker <russell@coker.com.au> writes:
> > It seems to me that /usr/libexec is a better name for such things, and
> > having the same directory names used across distributions provides real
> > benefits (copying config files and binaries from other distributions when
> > a bug stops a server working and it's REALLY important to get it fixed
> > fast).
> >
> > Should we change some of these to /usr/libexec?
>
> That would be /usr/libexec/arch-os/postfix vs /usr/lib/arch-os/postfix
> then.
>
> If you consider any change then please include the multiarch changes
> at the same time. No point doing 2 transitions for etch.
Why would it be desirable to have arch-os directories under libexec?
By definition anything in libexec is a program that is a part of another
program. In the case of Postfix there are many cooperating programs running
with different privs (different UID and different SE Linux domain) that are
used for different aspects of Postfix functionality. Why would you want one
of those programs to be 32bit and another to be 64bit?
Firstly there is little performance to be gained by running Postfix 64bit.
Any performance issues that a Postfix server will experience will be related
to disk IO (not a word size issue) or the speed of external programs such as
virus scanners and Postgrey (which interoperate with Postfix via TCP sockets
and have no inter-dependencies on word size etc).
Secondly there is no benefit to using different word sizes for different parts
of Postfix. I can't imagine any reason for using different word sizes.
There is a possibility of having Postfix call external shared objects which
may make some dependencies on word size. But if you have two shared objects
one of which is 32bit and another 64bit then trying to get Postfix processes
to use both will be a losing game. AFAIK there is no design documentation
which precisely states which Postfix sub-process will use a given shared
object.
Finally no-one has tested Postfix for such things. I think that Postfix is
very well written and should work even if you had parts of it being 64bit and
parts being 32bit. But this is not tested or guaranteed. If there was a bug
in this regard then it could have security implications, do you want to take
the chance?
--
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