1. 22 Sep, 2008 1 commit
    • Aristeu Rozanski's avatar
      x86, NMI watchdog: when booting with reset_devices, clear the performance counters · 28b166a7
      Aristeu Rozanski authored
      P4s have a quirk that makes necessary to clear P4_CCCR_OVF bit on the CCCR
      everytime the PMI is triggered. When booting the kernel with reset_devices
      (more specific kdump case), the counters reach zero and the PMI will be
      generated. This is not a problem on other processors but on P4s, it'll
      continue to generate NMIs until that bit is cleared. Since there may be
      other users of the performance counters, clear and disable all of them
      when booting with reset_devices option.
      
      We have a P4 box here that crashes because of this problem. Since the kdump
      kernel usually boots with only one processor active, the second logical
      unit won't be set up, therefore, MSR_P4_IQ_CCCR1 (and other performance
      counter registers) won't be cleared and P4_CCCR_OVF may be still set because
      the previous kernel was using this register. An NMI is triggered because of
      the MSR_P4_IQ_CCCR1 right after the NMI delivery is enabled, triggering the
      race fixed on my previous email.
      Signed-off-by: default avatarAristeu Rozanski <aris@redhat.com>
      Acked-by: default avatarDon Zickus <dzickus@redhat.com>
      Acked-by: default avatarPrarit Bhargava <prarit@redhat.com>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      28b166a7
  2. 21 Sep, 2008 11 commits
  3. 20 Sep, 2008 10 commits
  4. 19 Sep, 2008 18 commits