RE: dpkg and debhelper patches for lib64 support
Maybe I don't understand the suggestion, but be careful here about substituting 32-bit libraries for 64-bit ones. A 32-bit binary can't link to a 64-bit library. At least, not easily. Switching between instruction sets within a process is not supported in Linux today, and I don't know of anyone working on changing that behavior.
Having said that, there are times when you can substitute a 32-bit dependency. Not in the case of libraries, but if you need to execute a script, the interpreter (e.g. bash, perl, tcsh, python) can be 32-bit or 64-bit. At trade shows, we've also run 64-bit X apps within a 32-bit X environment to show how easily you can mix programs. I think that's possible because the X protocol is platform-independent, and only tells the local X server what to display. ...but within that 64-bit X application, each required library is 64-bit, and within the 32-bit X server, each required library is 32-bit (so you could have something like a libX.so.# existing in both lib and lib64 directories being accessed at the same time).
Most existing AMD64 distributions solved the problem by making all dependencies for a 64-bit package be 64-bit. That's the easiest way to go about it.
Personally, I'd love to see a Linux OS which correctly identifies situations where 32-bit packages can be substituted for 64-bit ones. If Debian did this, I think it would be the first truly hybrid 32-bit & 64-bit Linux distribution (all AMD64 distributions I know of are 64-bit with support for 32-bit packages and often both 64-bit and 32-bit development capabilities). But identifying that for each package is a non-trivial undertaking. I would be the last to volunteer.
-----Original Message-----
From: Gerhard Tonn [mailto:GerhardTonn@gammatau.de]
Sent: Tuesday, June 10, 2003 8:01 AM
To: GOTO Masanori
Cc: Joey Hess; debian-x86-64@lists.debian.org;
debian-dpkg@lists.debian.org
Subject: Re: dpkg and debhelper patches for lib64 support
On Tuesday 10 June 2003 03:17, you wrote:
> At Mon, 9 Jun 2003 16:26:17 +0200,
>
> Gerhard Tonn wrote:
> > I have made some changes to dpkg and debhelper in order to support
> > /lib64 and /usr/lib64 locations on 64 bit platforms. You find the patches
> > at people.debian.org/~gt/lib64 along with patches for a bunch of other
> > packages using the dpkg and debhelper extensions. Some of the patches
> > have been used already by Arnd Bergmann for the x86-64 port. Any feedback
> > is welcome.
>
> Excellent.
>
> > Assumptions:
> > ------------
> > Development packages for 32 and 64 bit platforms are not installable
> > concurrently.
>
> I don't still know about it, but
>
> * Is this assumption practical?
> * Should development packages be capable to handle both 32/64 bit at
> the same?
> * Are there any example development packages which need to split
> between for 32 and for 64 bit?
>
The assumption simplifies the lib64 support at least. If both 32 and 64 bit
development packages are needed concurrently, we could add the *.so link of
the 32 bit package to the 64 bit package instead. The dependencies have to be
adapted accordingly.
Regards,
Gerhard
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