Re: Bug#1035904: dpkg currently warning about merged-usr systems (revisited)
On Mon, 15 May 2023 at 01:14, Russ Allbery <rra@debian.org> wrote:
>
> Luca Boccassi <bluca@debian.org> writes:
>
> > Why would "software compiled on Debian" fail to work in other
> > environments? Well, there are many reasons actually, people invented
> > containers/flatpaks/snaps exactly for that reason. But nothing do with
> > anything discussed here though, as far as I can tell?
>
> My understanding is that this specific thread is about a mention that we
> may want to change PT_INTERP to /usr/lib64/ld-linux-x86-64.so.2 or some
> similar path.
>
> If PT_INTERP points to a file that doesn't exist, the program is obviously
> not going to run. The Linux x86_64 ABI says it must point to
> /lib64/ld-linux-x86-64.so.2. If we build binaries that use some other
> value, then we are not building ABI-compliant binaries and they may not
> run on other systems. This is the whole point of an ABI.
This is not about locally compiled software or such, only packages
(and maybe even just a subset of them).
> An obvious specific example of such a system would be one that didn't
> merge /usr and thus only had /lib64/ld-linux-x86-64.so.2 and not any other
> path, but that's just one obvious example. There may be others; the whole
> point of an ABI is that you do not change things like this, not even if
> you can't personally imagine why your change wouldn't be harmful. There's
> a whole process for changing an ABI that involves everyone else agreeing
> as well, and unless one goes through that process, the ABI is what it is.
> Debian not building ABI-compliant binaries would be highly surprising.
That's self-evidently not true, as there are other distributions where
that already happens, it's been already mentioned. Besides, we are not
talking about sacred religious texts - the point is making things
work. If they do, is it _really_ non-compliant/incompatible?
> Incidentally, that remains true even if we only do that in distribution
> packages. I certainly have copied binaries from a Debian package to other
> Linux systems before for various reasons and expected them to run. Sure,
> this might not work for other reasons outside of our control, but that's
> no reason to be gratuitously incompatible by breaking the ABI,
> particularly for what seem to be annoyances of our own creation with known
> workarounds.
Thanks, that's the first actual real example mentioned so far. And
it's an interesting one: taking a $random Debian package and using it
on a completely different, non-Debian system. Is that a supported use
case? If so, does that mean that I can go ahead and raise a Severity:
serious bug on any package that doesn't work in such a way?
Kind regards,
Luca Boccassi
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