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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. 2. 3. Actual results: SMP kernel. Expected results: Uniprocessor kernel. Additional info:
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.