PM: hibernate: Allow ACPI hardware signature to be honoured

[linux-2.6-microblaze.git] / Documentation / admin-guide / kernel-parameters.txt

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9725c54..10e0a3a 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -225,14 +225,23 @@
                        For broken nForce2 BIOS resulting in XT-PIC timer.
 
        acpi_sleep=     [HW,ACPI] Sleep options
-                       Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
-                                 old_ordering, nonvs, sci_force_enable, nobl }
+                       Format: { s3_bios, s3_mode, s3_beep, s4_hwsig,
+                                 s4_nohwsig, old_ordering, nonvs,
+                                 sci_force_enable, nobl }
                        See Documentation/power/video.rst for information on
                        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.
+                       s4_hwsig causes the kernel to check the ACPI hardware
+                       signature during resume from hibernation, and gracefully
+                       refuse to resume if it has changed. This complies with
+                       the ACPI specification but not with reality, since
+                       Windows does not do this and many laptops do change it
+                       on docking. So the default behaviour is to allow resume
+                       and simply warn when the signature changes, unless the
+                       s4_hwsig option is enabled.
                        s4_nohwsig prevents ACPI hardware signature from being
-                       used during resume from hibernation.
+                       used (or even warned about) during resume.
                        old_ordering causes the ACPI 1.0 ordering of the _PTS
                        control method, with respect to putting devices into
                        low power states, to be enforced (the ACPI 2.0 ordering