[M3devel] ROOT, $ORIGIN, runpath, LD_LIBRARY_PATH, symlinks, hardlinks, etc.

[Tony Hosking]

I think we are converging on a reasonable compromise (as noted in my  
other responses).

On 2 Jul 2009, at 15:59, Jay wrote:

> > copy and commit the source to cm3 is viable
> > I don't know what this sentence means.
>
> I don't have to be copying files around in the build order for cm3  
> to create hard links.
> I can just copy on my machine and commit to cvs a little bit of code  
> to do it.
> That isn't nearly as hacky.
>
> >  heck, use a relative instead of absolute from ROOT
>        > ditto
>
>
> $origin it turns out is very portable.
>   Every system we support except NetBSD 4.0 seems to have it, and  
> even some we don't currently support.
>   And NetBSD 5.0, which already released, has it.
>   And MacOSX is plenty close enough. It is a matter of relative to  
> the executable or the reference, and which OS version you support. I  
> believe newer versions relaly do have $origin by another name, but  
> 10.4 has relative to the executable, which is good enough to me.
>
> If you don't use $origin, then people either must install to the one  
> true place, or they must use LD_LIBRARY_PATH, or they must rebuild/ 
> relink/fixup themselves.
>
> LD_LIBRARY_PATH is widely panned.
> Having to rebuild seems onerous for most people.
> Having a choice of where to install? Important?
>
>
> > Right.  rpaths in the executable should do the trick.
>
> Just in the executable? Shouldn't they somewhat be in the shared  
> libraries?
> If foo uses libm3 and libm3 uses m3core and foo doesn't use m3core,  
> arguably foo shouldn't mention m3core, only libm3 should.
>
>
>  > Ideally we use the same approach for *all* platforms.  So, what  
> do all platforms have in common.
>
> $origin comes extremely close to that, and provides the benefit that  
> user can specify where to install.
>
>
>  > and if there is need for override use $LD_LIBRARY_PATH.
>
> But again (I know, I repeated myself, so you did, now I am), this  
> forces any install to non-default location to use LD_LIBRARY_PATH.  
> It is an option. But $origin is also /very/ portable...
>
>  >> But if everything goes in INSTALL_ROOT/lib we have only one  
> directory, right?
>
> Correct. That is what I achieved with the hardlinks, and will try to  
> achieve shortly without them.
>
>  > Surely, building for a distro can build in the right path.
>
> Not really. It would disrupt the running multiuser system.
> But it can probably use -rpath to stick paths in that don't  
> correspond to the "staging" area.
>
>
>  > Where did /tmp/cm3 come from?
>
> The distribution builds in /tmp. You don't have to be root or  
> disrupt the running machine to build a distribution.
> There a question maybe of if the resulting files should be owned by  
> root?
>
>
>  > Elegance is also a concern.
>
> Agreed. Copying files in the build isn't elegant. The result is  
> elegant imho.
> Hardlinks aren't elegant? I don't know.
> Anyway, ok, I'll just put the files in lib and no hardlinks, I'll  
> try that.
> > Now, keep in mind, that unshipped binaries sometimes people like  
> to work
>  > I don't know understand what you are trying to say here.
>
> Let me think about unshipped binaries later..
> One thing is that $origin doesn't work with unshipped binaries.
> By default we put in both $origin and the full path you like.
> But imho distributions should just have $origin.
> Or if user can't chose install location, maybe just the full path.
> The big question is if user can chose where to install.
> On birch I use $HOME/cm3.
> Seems kind of important/useful?
>
>
>  - Jay
>

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