posted by delano

I was trying to install the sys-utils Ruby libraries today and got an error while building sys-cpu on OX 10.5 Leopard. sys-cpu is a multi-platform Ruby library for accessing information about the CPUs and it contains a native extension which needs to be compiled during them installation. This is the error:

$ sudo gem install sys-cpu
  Building native extensions.  This could take a while...
  ERROR:  Error installing sys-cpu:
  ERROR: Failed to build gem native extension.
  ...
  cpu.c:14:17: error: kvm.h: No such file or directory
  cpu.c:14:17: error: kvm.h: No such file or directory
  cpu.c: In function 'cpu_load_avg':
  ...
  make: *** [cpu.o] Error 1

OS X 10.5 seems to be missing a C header file, kvm.h, that’s required by sys-cpu. Here’s how you can solve the problem:

• Download a non-gem version and unpack it.
• Get a copy of kvm.h. If you’re running OS X 10.5 that was upgraded from 10.4, you can find it in /Developer/SDKs/MacOSX10.4.sdk/usr/include. If not, you can download it from here: http://solutious.com/r/kvm.h.
• Copy kvm.h in to sys-cpu-0.6.0/ext
• Inside of sys-cpu-0.6.0, run: rake test then sudo rake install
• The following command should now run without errors: ruby -r'sys/cpu' -e 1.

That’s it!