From 75a048119e76540d73132cfc8e0fa0c0a8bb6c83 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Thu, 22 Jan 2009 16:17:05 -0800 Subject: x86: handle PAT more like other CPU features Impact: Cleanup When PAT was originally introduced, it was handled specially for a few reasons: - PAT bugs are hard to track down, so we wanted to maintain a whitelist of CPUs. - The i386 and x86-64 CPUID code was not yet unified. Both of these are now obsolete, so handle PAT like any other features, including ordinary feature blacklisting due to known bugs. Signed-off-by: H. Peter Anvin --- arch/x86/mm/pat.c | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-) (limited to 'arch/x86/mm/pat.c') diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 8b08fb95527..430cb44dd3f 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -30,7 +30,7 @@ #ifdef CONFIG_X86_PAT int __read_mostly pat_enabled = 1; -void __cpuinit pat_disable(char *reason) +void __cpuinit pat_disable(const char *reason) { pat_enabled = 0; printk(KERN_INFO "%s\n", reason); @@ -42,6 +42,11 @@ static int __init nopat(char *str) return 0; } early_param("nopat", nopat); +#else +static inline void pat_disable(const char *reason) +{ + (void)reason; +} #endif @@ -78,16 +83,20 @@ void pat_init(void) if (!pat_enabled) return; - /* Paranoia check. */ - if (!cpu_has_pat && boot_pat_state) { - /* - * If this happens we are on a secondary CPU, but - * switched to PAT on the boot CPU. We have no way to - * undo PAT. - */ - printk(KERN_ERR "PAT enabled, " - "but not supported by secondary CPU\n"); - BUG(); + if (!cpu_has_pat) { + if (!boot_pat_state) { + pat_disable("PAT not supported by CPU."); + return; + } else { + /* + * If this happens we are on a secondary CPU, but + * switched to PAT on the boot CPU. We have no way to + * undo PAT. + */ + printk(KERN_ERR "PAT enabled, " + "but not supported by secondary CPU\n"); + BUG(); + } } /* Set PWT to Write-Combining. All other bits stay the same */ -- cgit v1.2.3