Using FC3 RPM's in FC4

Hi all. I am so excited about FC4 that I have June 6th circled on my calendar
However, knowing that it will take some time for all my favourite apps to be made into FC4 RPM's, I was wondering something. How much trouble would I cause myself if I installed FC3 RPM's on an FC4 system? As I see it, I have two choices: 1. Install FC4 as soon as it's available and install all my favourite FC3 RPM's.. or.. 2. keep running FC3 and wait to install FC4 until the FC4 RPM's have been built for my favourite apps.

How bad is it to install FC3 RPM's on FC4?

[AndyGreen]

Assuming your FC3 external app rpm was packaged well, RPM will let you know if things are not right for that rpm. You'll get errors telling you that your FC3 rpm requires such and such library version where FC4 has a later version. If you see this just accept that it won't work, don't force it.

If you can get a source RPM for your external app, you can tell RPM to rebuild it, in which case it will attempt to link to whatever libraries are around on your FC4 system. This will either work or fail depending on possible changes to the library ABI (ie, if functions in the later library got removed or arguments added, etc it will fail).

[robghealey]

I have tried using several fc.src.rpm on FC4, and it seems to fail so far...

I tried synaptic, and nessus multiple times...

Originally Posted by AndyGreen

Assuming your FC3 external app rpm was packaged well, RPM will let you know if things are not right for that rpm. You'll get errors telling you that your FC3 rpm requires such and such library version where FC4 has a later version. If you see this just accept that it won't work, don't force it.

If you can get a source RPM for your external app, you can tell RPM to rebuild it, in which case it will attempt to link to whatever libraries are around on your FC4 system. This will either work or fail depending on possible changes to the library ABI (ie, if functions in the later library got removed or arguments added, etc it will fail).

I didn't think about source RPM's, thank you for mentioning it. I can just use them to build my own rpm's on FC4, great idea! The command "rpmbuild -ba <packagename>.spec" builds rpm's from source code tarballs, but what is the command to build an rpm from a source rpm? Is it "rpmrebuild -ba <packagename>.spec" - using rpmrebuild instead of rpmbuild? Is that correct?

Cool, I can just install FC4 and spend some time rebuilding source rpm's.

[james_in_denver]

Source "RPM"s will probably work okay, compiled RPM'S almost certainly won't work.

FC3 rpm's are built using gcc 3.x.

FC4 rpm's are compiled with gcc 4.x.

I am pretty certain that the "shared libraries" and binary executables between the two versions will be incompatible.

Originally Posted by james_in_denver

Source "RPM"s will probably work okay, compiled RPM'S almost certainly won't work.

FC3 rpm's are built using gcc 3.x.

FC4 rpm's are compiled with gcc 4.x.

I am pretty certain that the "shared libraries" and binary executables between the two versions will be incompatible.

aha, ok. Thanks for the info, that explains a lot.

When I do get FC4 installed, what is the proper command to rebuild a .src.rpm? I know it is "rpmbuild -ba packagename.spec" for building rpm's, but what is the command for rebuilding .src.rpm rpm's?

[Vinneh]

It may be bad practice, but I've noticed that every FC3 package I've installed so far has worked

[FNM]

I installed the Skype FC3 RPM from their website on FC4, and it works perfect.

[crackers]

It's pretty much hit or miss with binary RPMs. The ones that will work probably don't rely that heavily on "system" APIs and the libraries they do use haven't changed their APIs. Of course, that means the ones that won't work wil fail in unpredictable ways - which could end up being really bad, depending upon the application(s).