static bool __read_mostly pat_initialized;
static bool __read_mostly init_cm_done;
-void pat_disable(const char *reason)
+/*
+ * PAT support is enabled by default, but can be disabled for
+ * various user-requested or hardware-forced reasons:
+ */
+void pat_disable(const char *msg_reason)
{
if (pat_disabled)
return;
}
pat_disabled = true;
- pr_info("x86/PAT: %s\n", reason);
+ pr_info("x86/PAT: %s\n", msg_reason);
}
static int __init nopat(char *str)
{
- pat_disable("PAT support disabled.");
+ pat_disable("PAT support disabled via boot option.");
return 0;
}
early_param("nopat", nopat);
u64 tmp_pat;
if (!boot_cpu_has(X86_FEATURE_PAT)) {
- pat_disable("PAT not supported by CPU.");
+ pat_disable("PAT not supported by the CPU.");
return;
}
rdmsrl(MSR_IA32_CR_PAT, tmp_pat);
if (!tmp_pat) {
- pat_disable("PAT MSR is 0, disabled.");
+ pat_disable("PAT support disabled by the firmware.");
return;
}
}
/**
- * pat_init - Initialize PAT MSR and PAT table
+ * pat_init - Initialize the PAT MSR and PAT table on the current CPU
*
* This function initializes PAT MSR and PAT table with an OS-defined value
* to enable additional cache attributes, WC, WT and WP.
u64 pat;
struct cpuinfo_x86 *c = &boot_cpu_data;
+#ifndef CONFIG_X86_PAT
+ pr_info_once("x86/PAT: PAT support disabled because CONFIG_X86_PAT is disabled in the kernel.\n");
+#endif
+
if (pat_disabled)
return;