4 files changed, 23 insertions, 3 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e0f346d201ed..1d089eeff3cf 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -149,7 +149,8 @@ and is between 256 and 4096 characters. It is defined in the file
                         default: 0
 
         acpi_sleep=     [HW,ACPI] Sleep options
-                        Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
+                        Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
+                                  old_ordering, s4_nonvs }
                         See Documentation/power/video.txt for s3_bios and s3_mode.
                         s3_beep is for debugging; it makes the PC's speaker beep
                         as soon as the kernel's real-mode entry point is called.
@@ -159,6 +160,8 @@ and is between 256 and 4096 characters. It is defined in the file
                         control method, wrt putting devices into low power
                         states, to be enforced (the ACPI 2.0 ordering of _PTS is
                         used by default).
+                        s4_nonvs prevents the kernel from saving/restoring the
+                        ACPI NVS memory during hibernation.
 
         acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
                         Format: { level | edge | high | low }
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 806b4e9051b4..707c1f6f95fa 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -159,6 +159,8 @@ static int __init acpi_sleep_setup(char *str)
 #endif
                 if (strncmp(str, "old_ordering", 12) == 0)
                         acpi_old_suspend_ordering();
+                if (strncmp(str, "s4_nonvs", 8) == 0)
+                        acpi_s4_no_nvs();
                 str = strchr(str, ',');
                 if (str != NULL)
                         str += strspn(str, ", \t");
diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c
index 45a8015e4217..bef41fd4c877 100644
--- a/drivers/acpi/sleep/main.c
+++ b/drivers/acpi/sleep/main.c
@@ -101,6 +101,19 @@ void __init acpi_old_suspend_ordering(void)
  * cases.
  */
 static bool set_sci_en_on_resume;
+/*
+ * The ACPI specification wants us to save NVS memory regions during hibernation
+ * and to restore them during the subsequent resume.  However, it is not certain
+ * if this mechanism is going to work on all machines, so we allow the user to
+ * disable this mechanism using the 'acpi_sleep=s4_nonvs' kernel command line
+ * option.
+ */
+static bool s4_no_nvs;
+
+void __init acpi_s4_no_nvs(void)
+{
+        s4_no_nvs = true;
+}
 
 /**
  *      acpi_pm_disable_gpes - Disable the GPEs.
@@ -396,7 +409,7 @@ static int acpi_hibernation_begin(void)
 {
         int error;
 
-        error = hibernate_nvs_alloc();
+        error = s4_no_nvs ? 0 : hibernate_nvs_alloc();
         if (!error) {
                 acpi_target_sleep_state = ACPI_STATE_S4;
                 acpi_sleep_tts_switch(acpi_target_sleep_state);
@@ -494,7 +507,8 @@ static int acpi_hibernation_begin_old(void)
         error = acpi_sleep_prepare(ACPI_STATE_S4);
 
         if (!error) {
-                error = hibernate_nvs_alloc();
+                if (!s4_no_nvs)
+                        error = hibernate_nvs_alloc();
                 if (!error)
                         acpi_target_sleep_state = ACPI_STATE_S4;
         }
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index fba8051fb297..dfa0a5356c53 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -270,6 +270,7 @@ int acpi_check_mem_region(resource_size_t start, resource_size_t n,
 #ifdef CONFIG_PM_SLEEP
 void __init acpi_no_s4_hw_signature(void);
 void __init acpi_old_suspend_ordering(void);
+void __init acpi_s4_no_nvs(void);
 #endif /* CONFIG_PM_SLEEP */
 #else   /* CONFIG_ACPI */