Description of problem: Presently there is a "--with smp" kernel.spec option for use with rpmbuild. However, all current kernel config files except arm and powerpc32-generic enable the smp option. For most architectures you cannot opt-out of smp using "--with up".
Version-Release number of selected component (if applicable): RHEL > 4
How reproducible: 100%
Steps to Reproduce:
1. Build a kernel using rpmbuild and '--with up'. It will NOT build a uniprocessor kernel because the config files override it.
Actual results: SMP kernel.
Expected results: Uniprocessor kernel.
An x86 SMP kernel will realize there is only one CPU and patch out various sections of SMP code to act as a UP kernel. Why do we need to force a UP kernel?
We need to force a UP kernel on systems that have > 1 core, but you want to test UP behavior. It's not the same as setting MAXCPUS=1.
Created attachment 518300 [details]
Fix with_up to work
I'm not sure who "we" is in this context, but something like the attached patch would be needed. I wouldn't expect Fedora to build this by default at all, but it would make the with_up setting a viable option for those wanting to do that kind of debugging with a local build.
I'm hesitant to further ugly up the spec & config set with something this niche.
We don't ship UP builds, so this is purely a minority development knob.
Rather than make the rats-nest of config generation even more complicated, I'm closing this WONTFIX. If you want to do a build with config options we don't ship/support, either make those changes locally, or do a non-rpm based build.