[PATCH] x86: set Pentium M as PAE capable

From: Chris Bainbridge
Date: Tue Feb 25 2014 - 01:02:13 EST


Pentium M is PAE capable but does not indicate so in the CPUID response.
This is an issue now that some distributions are no longer shipping
non-PAE kernels (those distributions no longer boot on Pentium M). This
small patch fixes the issue by forcing the PAE capability on Pentium M.

For more discussion see https://bugs.launchpad.net/baltix/+bug/930447

Signed-off-by: Chris Bainbridge <chris.bainbridge@xxxxxxxxx>

---

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index bbe1b8b..97996aa 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -226,6 +226,12 @@ static void intel_workarounds(struct cpuinfo_x86 *c)
clear_cpu_cap(c, X86_FEATURE_SEP);

/*
+ * PAE CPUID bug: Pentium M reports no PAE but has PAE
+ */
+ if ((c->x86 == 6) && ((c->x86_model == 9) || (c->x86_model == 13)))
+ set_cpu_cap(c, X86_FEATURE_PAE);
+
+ /*
* P4 Xeon errata 037 workaround.
* Hardware prefetcher may cause stale data to be loaded into the cache.
*/
--
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