On 10/21/10 3:33 AM, Qing He wrote:

I recently reported several zypper bugs specifically for arm, after
some deeper investigation, the problem seems to be of higher level than
I originally thought.

The root cause is that zypper and poky use different way to represent
architectures, as we are putting them together, these two ways are
not compatible, causing many minor glitches that need to modify at
least one of them.

Poky has three kinds of representations in a single target image, which
are independent, cpu-dependent and machine-dependent (all, armv5te,
qemuarm, respectively), e.g.

update-rc.d-0.7-r3.all.rpm
curl-7.21.0-r0.armv5te.rpm
task-base-1.0-r69.qemuarm.rpm

(note that armv5te is the same with gcc's -march option, meaning little
endian)

This is natural until zypper is involved. Zypper supports only one arch
at one time (and this arch should not be changed in fly), and use the
idea of arch compatibility (e.g. _noarch is compatible with _i586), it
then hardcodes the available archs in a different way than poky does,
thus creating several problems:
1. what uses for independent packages is called "noarch", "all" is not
recognized, something depends on update-rc.d won't be installed
because of missing dependency

We can certainly look into translating "all" to "noarch" post 0.9. That might make it easier for people coming from the RPM world, to understand what is in the package.

2. the arch automatic detection system uses "uname -m", thus producing
armv5tejl, which can only be resolved as armv5tel, conflicting with
"armv5te" in rpm

This is a bug in Zypper. The machine names should come from somewhere other then uname -m. (The value of uname -m is very much ia32 specific for the most part.. other architectures have way too many possible namings for it to be useful.) There is a line in "/etc/rpm/platform" that contains the name of Poky architecture. This file should be referenced (instead of -m) for all cases.

3. many archs are missing in zypper, like mips, armeb, etc.
4. there is no concept of machine-dependent packages (task-base) in
zypper, although we can work around.

Generally speaking, this is true of most RPM installations. However, within RPM itself.. there really isn't any concept of "arch" anymore.. They're really only used for grouping and ordering. So Zypper may need to be updated to query the arch of a package and use it for it's various operations.

Currently, at least zypper is broken on all of mips, arm, ppc, with
slightly different problems.

The ideal situation is to use consistent arch specification, the
following can be a solution:
1. rename *.all.rpm to *.noarch.rpm

We can certainly do this easily.

2. removing the concept of machine-dependent packages, change all
*.qemuarm.rpm to *.armv5te.rpm

I'm a bit worried about doing this, as we'll end up with (potentially) incompatible packages with exactly the same name and versions... Perhaps we need to think about embedding the machine type into the name of the packages instead?

3. enhance zypper arch module, make the addition more flexible,
allowing arch alias (e.g. armv5te = armv5tel = armel = arm)

Zypper should read the rpm platform file.

That would be some work to do, maybe 1.0 is a good time to get zypper
and package upgrade truely working.

Yes, we also need to get multi-arch as well.. (i.e. 32-bit and 64-bit at the same time) working. I'm guessing there will be some Zypper interactions there as well.

--Mark

Any ideas and comments?

Thanks,
Qing
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