Red Hat Bugzilla – Bug 68329
No /proc/profile support without CONFIG_SMP
Last modified: 2007-04-18 12:43:59 EDT
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Description of problem:
It is impossible to build a kernel with data in /proc/profile without building
SMP. The culprit seems to be the patch linux-2.4.9-nmiprofiling.patch, which
removes the code without even adding a CONFIG_NMI or like.
Surely some explanation is due at the least.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Add profile=# to your non-SMP kernel command line
3. cat /proc/profile
4. Spend about an hour messing with readprofile before pulling the source, then
looking at the obscure undocumented patches in the 2.4.18-3 kernel rpm.
Actual Results: There is nothing in /proc/profile!
Expected Results: There should be useful data there.
It's always disappointing to find features deleted in redhat packages, with no
Correction: it is CONFIG_X86_LOCAL_APIC, which is on by default in defconfig and
in the package.
It is still unfortunate that without this option there is no /proc/profile, but
it is a more acceptable workaround than setting CONFIG_SMP.
Actually the nmiprofiling patch cuts profiling out of every code path but the
NMI event itself, so even enabling the local APIC is not a workaround.
fixed in current erratum