ACPI / Sleep: Allow the NVS saving to be skipped during suspend to RAM

Commit 2a6b69765a
(ACPI: Store NVS state even when entering suspend to RAM) caused the
ACPI suspend code save the NVS area during suspend and restore it
during resume unconditionally, although it is known that some systems
need to use acpi_sleep=s4_nonvs for hibernation to work.  To allow
the affected systems to avoid saving and restoring the NVS area
during suspend to RAM and resume, introduce kernel command line
option acpi_sleep=nonvs and make acpi_sleep=s4_nonvs work as its
alias temporarily (add acpi_sleep=s4_nonvs to the feature removal
file).

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=16396 .

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-and-tested-by: tomas m <tmezzadra@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>

arch/x86/kernel/acpi/sleep.c

@@ -157,9 +157,14 @@ static int __init acpi_sleep_setup(char *str)
 #ifdef CONFIG_HIBERNATION
 		if (strncmp(str, "s4_nohwsig", 10) == 0)
 			acpi_no_s4_hw_signature();
-		if (strncmp(str, "s4_nonvs", 8) == 0)
-			acpi_s4_no_nvs();
+		if (strncmp(str, "s4_nonvs", 8) == 0) {
+			pr_warning("ACPI: acpi_sleep=s4_nonvs is deprecated, "
+					"please use acpi_sleep=nonvs instead");
+			acpi_nvs_nosave();
+		}
 #endif
+		if (strncmp(str, "nonvs", 5) == 0)
+			acpi_nvs_nosave();
 		if (strncmp(str, "old_ordering", 12) == 0)
 			acpi_old_suspend_ordering();
 		str = strchr(str, ',');