multiarch doesn't really work

[Brian J. Murrell]

So, following along with https://wiki.ubuntu.com/MultiarchSpec and specifically the (Shawn) use-case of upgrading an i386 system to amd64, I've upgraded the kernel to amd64 and booted it successfully. I've also got the required amd64 libs installed and I've successfully upgrade dpkg and apt to the amd64 versions.

# dpkg --print-architecture
amd64
# dpkg --print-foreign-architectures
i386

I thought at this point I was supposed to have a happy dual-arch based system, but that doesn't seem to be the case. apt-get check lists a whole litany of dependency failures. But to just take the first one for example:

# apt-get check
...
adduser : Depends: perl-base (>= 5.6.0) but it is not installable
...

dpkg shows the following states for those packages:
ii adduser 3.113ubuntu2 add and remove users and groups
in perl-base <none> (no description available)
ii perl-base:i386 5.14.2-6ubuntu2 minimal Perl system

So the question is, is the perl-base:i386 package not enough to satisfy adduser's dependency on perl-base? If not, then there is no hope that multi-arch can be at all useful and I will need to upgrade everything to amd64 right?

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: apt (not installed)
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14
Uname: Linux 3.2.0-24-generic x86_64
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
Date: Sun Jun 24 23:29:43 2012
ProcEnviron:
 TERM=screen
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: apt
UpgradeStatus: No upgrade log present (probably fresh install)

[David Kalnischkies (donkult)]

Nobody said that crossgrades are supported yet, but even then it is not a problem in APT. A foreign package like perl-base which is not marked accordingly can't satisfy a dependency for a native packages and v.v. as it is defined in the spec (I suppose dpkg is equally unhappy about the current system: dpkg --audit). So yes, you shouldn't "upgrade" your i386 systems to amd64 just yet now that we barely can install some packages from i386 on amd64.

You need to crossgrade at least a couple more packages (at least essential set) by hand for now to fix your system - closing as invalid as APT is able to cope with a mixed system, but the packages need to support that, which they are not currently. So you might want to refer to reporting bugs and patches to packages which are not yet multiarchified.