diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/boot/cpucheck.c | 20 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 19 |
2 files changed, 39 insertions, 0 deletions
diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c index 100a9a1..f0d0b20 100644 --- 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) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 34bbb55..897d620 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -186,6 +186,14 @@ static void intel_smp_check(struct cpuinfo_x86 *c) } } +static int forcepae; +static int __init forcepae_setup(char *__unused) +{ + forcepae = 1; + return 1; +} +__setup("forcepae", forcepae_setup); + static void intel_workarounds(struct cpuinfo_x86 *c) { #ifdef CONFIG_X86_F00F_BUG @@ -214,6 +222,17 @@ static void intel_workarounds(struct cpuinfo_x86 *c) clear_cpu_cap(c, X86_FEATURE_SEP); /* + * PAE CPUID issue: many Pentium M report no PAE but may have a + * functionally usable PAE implementation. + * Forcefully enable PAE if kernel parameter "forcepae" is present. + */ + if (forcepae) { + printk(KERN_WARNING "PAE forced!\n"); + set_cpu_cap(c, X86_FEATURE_PAE); + add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_NOW_UNRELIABLE); + } + + /* * P4 Xeon errata 037 workaround. * Hardware prefetcher may cause stale data to be loaded into the cache. */ |