Merge commit 'e26a9e0' into stable/for-linus-3.15

[cascardo/linux.git] / arch / x86 / boot / cpucheck.c

diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index 100a9a1..f0d0b20 100644 (file)
--- a/arch/x86/boot/cpucheck.c
+++ b/arch/x86/boot/cpucheck.c
@@ -67,6 +67,13 @@ static int is_transmeta(void)
               cpu_vendor[2] == A32('M', 'x', '8', '6');
 }
 
+static int is_intel(void)
+{
+       return cpu_vendor[0] == A32('G', 'e', 'n', 'u') &&
+              cpu_vendor[1] == A32('i', 'n', 'e', 'I') &&
+              cpu_vendor[2] == A32('n', 't', 'e', 'l');
+}
+
 /* Returns a bitmask of which words we have error bits in */
 static int check_cpuflags(void)
 {
@@ -153,6 +160,19 @@ int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr)
                asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
 
                err = check_cpuflags();
+       } else if (err == 0x01 &&
+                  !(err_flags[0] & ~(1 << X86_FEATURE_PAE)) &&
+                  is_intel() && cpu.level == 6 &&
+                  (cpu.model == 9 || cpu.model == 13)) {
+               /* PAE is disabled on this Pentium M but can be forced */
+               if (cmdline_find_option_bool("forcepae")) {
+                       puts("WARNING: Forcing PAE in CPU flags\n");
+                       set_bit(X86_FEATURE_PAE, cpu.flags);
+                       err = check_cpuflags();
+               }
+               else {
+                       puts("WARNING: PAE disabled. Use parameter 'forcepae' to enable at your own risk!\n");
+               }
        }
 
        if (err_flags_ptr)