RPM dependency rationale (and kernel packages)?
Jos Vos
jos at xos.nl
Tue Aug 19 17:04:21 UTC 2003
Hi,
Short intro:
Every package provides itself implicitly, as if the line
"Provides: foo = 5.0-2" was in the spec file. This means that any
dependency on "foo", "foo = 5.0", or "foo = 5.0-2" is satisfied
(as well as relational dependencies, like "foo >= 5.0" etc.).
This is all the basic RPM dependency behaviour and pretty
straightforward.
It now seems that rpm also has the following behaviour:
If you put an explicit "Provides" line in the spec file *omitting*
the release, say "Provides: foo = 5.0", then *any* dependency on
version 5.0 of foo, whatever release is required (!), is satisfied.
So, a package having "Require: foo = 5.0-6" happily coexists with
the foo-5.0-2 package. I don't understand this. Or it's a bug,
or there is some rationale for this that I don't know of (yet).
It also is the case that every kernel package provides
"kernel = %{version}" explicitly. AFAIK this is mainly done to let
kernel-smp, kernel-bigmem, etc. all "provide" the basic kernel too
(but Arjan can tell much more about this, see also our disussion
on https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=102639
earlier today).
In my case, I wanted to let a pseudo-package require specifically
"kernel = 2.4.20-18.9", to pull that kernel package in with APT
(more details on request) and I then detected that "kernel-2.4.20-8"
was good enough for rpm (and APT) to satisfy "kernel = 2.4.20-18.9".
So, now the main issues:
- Is the rpm bahaviour a bug or a feauture (if a feature, why)?
- Arjan has good reasons for the current kernel provides lines,
but I'm mainly objecting against the rpm bahaviour, so could
a different behaviour coexist with Arjans kernel packaging goals?
Note that the bug report Panu submitted (see above) mainly resulted
in a kernel packaging discussion, although the core question lays
at the rpm level.
--
-- Jos Vos <jos at xos.nl>
-- X/OS Experts in Open Systems BV | Phone: +31 20 6938364
-- Amsterdam, The Netherlands | Fax: +31 20 6948204
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