|author||Pavel Machek <email@example.com>||2006-03-23 03:00:02 -0800|
|committer||Linus Torvalds <firstname.lastname@example.org>||2006-03-23 07:38:07 -0800|
|parent||[PATCH] kernel/power: move externs to header files (diff)|
[PATCH] swsusp: documentation updates
Update suspend-to-RAM documentation with new machines, and makes message when processes can't be stopped little clearer. (In one case, waiting longer actually did help). From: "Rafael J. Wysocki" <email@example.com> Warn in the documentation that data may be lost if there are some filesystems mounted from USB devices before suspend. [Thanks to Alan Stern for providing the answer to the question in the Q:-A: part.] Signed-off-by: Pavel Machek <firstname.lastname@example.org> Signed-off-by: Rafael J. Wysocki <email@example.com> Signed-off-by: Andrew Morton <firstname.lastname@example.org> Signed-off-by: Linus Torvalds <email@example.com>
Diffstat (limited to 'Documentation')
2 files changed, 77 insertions, 48 deletions
diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt
index b28b7f04abb8..d7814a113ee1 100644
@@ -17,6 +17,11 @@ Some warnings, first.
* but it will probably only crash.
* (*) suspend/resume support is needed to make it safe.
+ * If you have any filesystems on USB devices mounted before suspend,
+ * they won't be accessible after resume and you may lose data, as though
+ * you have unplugged the USB devices with mounted filesystems on them
+ * (see the FAQ below for details).
You need to append resume=/dev/your_swap_partition to kernel command
line. Then you suspend by
@@ -27,19 +32,18 @@ echo shutdown > /sys/power/disk; echo disk > /sys/power/state
echo platform > /sys/power/disk; echo disk > /sys/power/state
+. If you have SATA disks, you'll need recent kernels with SATA suspend
+support. For suspend and resume to work, make sure your disk drivers
+are built into kernel -- not modules. [There's way to make
+suspend/resume with modular disk drivers, see FAQ, but you probably
+should not do that.]
If you want to limit the suspend image size to N bytes, do
echo N > /sys/power/image_size
before suspend (it is limited to 500 MB by default).
-Encrypted suspend image:
-If you want to store your suspend image encrypted with a temporary
-key to prevent data gathering after resume you must compile
-crypto and the aes algorithm into the kernel - modules won't work
-as they cannot be loaded at resume time.
Article about goals and implementation of Software Suspend for Linux
@@ -333,4 +337,37 @@ init=/bin/bash, then swapon and starting suspend sequence manually
usually does the trick. Then it is good idea to try with latest
+Q: How can distributions ship a swsusp-supporting kernel with modular
+disk drivers (especially SATA)?
+A: Well, it can be done, load the drivers, then do echo into
+/sys/power/disk/resume file from initrd. Be sure not to mount
+anything, not even read-only mount, or you are going to lose your
+Q: How do I make suspend more verbose?
+A: If you want to see any non-error kernel messages on the virtual
+terminal the kernel switches to during suspend, you have to set the
+kernel console loglevel to at least 5, for example by doing
+ echo 5 > /proc/sys/kernel/printk
+Q: Is this true that if I have a mounted filesystem on a USB device and
+I suspend to disk, I can lose data unless the filesystem has been mounted
+A: That's right. It depends on your hardware, and it could be true even for
+suspend-to-RAM. In fact, even with "-o sync" you can lose data if your
+programs have information in buffers they haven't written out to disk.
+If you're lucky, your hardware will support low-power modes for USB
+controllers while the system is asleep. Lots of hardware doesn't,
+however. Shutting off the power to a USB controller is equivalent to
+unplugging all the attached devices.
+Remember that it's always a bad idea to unplug a disk drive containing a
+mounted filesystem. With USB that's true even when your system is asleep!
+The safest thing is to unmount all USB-based filesystems before suspending
+and remount them after resuming.
diff --git a/Documentation/power/video.txt b/Documentation/power/video.txt
index 912bed87c758..d18a57d1a531 100644
@@ -1,7 +1,7 @@
Video issues with S3 resume
- 2003-2005, Pavel Machek
+ 2003-2006, Pavel Machek
During S3 resume, hardware needs to be reinitialized. For most
devices, this is easy, and kernel driver knows how to do
@@ -15,6 +15,27 @@ run normally so video card is normally initialized. It should not be
problem for S1 standby, because hardware should retain its state over
+We either have to run video BIOS during early resume, or interpret it
+using vbetool later, or maybe nothing is neccessary on particular
+system because video state is preserved. Unfortunately different
+methods work on different systems, and no known method suits all of
+Userland application called s2ram has been developed; it contains long
+whitelist of systems, and automatically selects working method for a
+given system. It can be downloaded from CVS at
+www.sf.net/projects/suspend . If you get a system that is not in the
+whitelist, please try to find a working solution, and submit whitelist
+entry so that work does not need to be repeated.
+Currently, VBE_SAVE method (6 below) works on most
+systems. Unfortunately, vbetool only runs after userland is resumed,
+so it makes debugging of early resume problems
+hard/impossible. Methods that do not rely on userland are preferable.
There are a few types of systems where video works after S3 resume:
(1) systems where video state is preserved over S3.
@@ -104,6 +125,7 @@ HP NX7000 ??? (*)
HP Pavilion ZD7000 vbetool post needed, need open-source nv driver for X
HP Omnibook XE3 athlon version none (1)
HP Omnibook XE3GC none (1), video is S3 Savage/IX-MV
+HP Omnibook 5150 none (1), (S1 also works OK)
IBM TP T20, model 2647-44G none (1), video is S3 Inc. 86C270-294 Savage/IX-MV, vesafb gets "interesting" but X work.
IBM TP A31 / Type 2652-M5G s3_mode (3) [works ok with BIOS 1.04 2002-08-23, but not at all with BIOS 1.11 2004-11-05 :-(]
IBM TP R32 / Type 2658-MMG none (1)
@@ -120,18 +142,24 @@ IBM ThinkPad T42p (2373-GTG) s3_bios (2)
IBM TP X20 ??? (*)
IBM TP X30 s3_bios (2)
IBM TP X31 / Type 2672-XXH none (1), use radeontool (http://fdd.com/software/radeon/) to turn off backlight.
-IBM TP X32 none (1), but backlight is on and video is trashed after long suspend
+IBM TP X32 none (1), but backlight is on and video is trashed after long suspend. s3_bios,s3_mode (4) works too. Perhaps that gets better results?
IBM Thinkpad X40 Type 2371-7JG s3_bios,s3_mode (4)
+IBM TP 600e none(1), but a switch to console and back to X is needed
Medion MD4220 ??? (*)
Samsung P35 vbetool needed (6)
-Sharp PC-AR10 (ATI rage) none (1)
+Sharp PC-AR10 (ATI rage) none (1), backlight does not switch off
Sony Vaio PCG-C1VRX/K s3_bios (2)
Sony Vaio PCG-F403 ??? (*)
+Sony Vaio PCG-GRT995MP none (1), works with 'nv' X driver
+Sony Vaio PCG-GR7/K none (1), but needs radeonfb, use radeontool (http://fdd.com/software/radeon/) to turn off backlight.
Sony Vaio PCG-N505SN ??? (*)
Sony Vaio vgn-s260 X or boot-radeon can init it (5)
+Sony Vaio vgn-S580BH vga=normal, but suspend from X. Console will be blank unless you return to X.
+Sony Vaio vgn-FS115B s3_bios (2),s3_mode (4)
Toshiba Libretto L5 none (1)
-Toshiba Satellite 4030CDT s3_mode (3)
-Toshiba Satellite 4080XCDT s3_mode (3)
+Toshiba Portege 3020CT s3_mode (3)
+Toshiba Satellite 4030CDT s3_mode (3) (S1 also works OK)
+Toshiba Satellite 4080XCDT s3_mode (3) (S1 also works OK)
Toshiba Satellite 4090XCDT ??? (*)
Toshiba Satellite P10-554 s3_bios,s3_mode (4)(****)
Toshiba M30 (2) xor X with nvidia driver using internal AGP
@@ -151,39 +179,3 @@ Asus A7V8X nVidia RIVA TNT2 model 64 s3_bios,s3_mode (4)
(***) To be tested with a newer kernel.
(****) Not with SMP kernel, UP only.
-(with thanks to Carl-Daniel Hailfinger)
-First, boot into X and run the following script ONCE:
-mkdir -p $statedir
-vbetool vbestate save >$statedir/vbe
-To suspend and resume properly, call the following script as root:
-fuser /dev/tty$curcons 2>/dev/null|xargs ps -o comm= -p|grep -q X && chvt 2
-cat /dev/vcsa >$statedir/vcsa
-echo 3 >/proc/acpi/sleep
-vbetool vbestate restore <$statedir/vbe
-cat $statedir/vcsa >/dev/vcsa
-Unless you change your graphics card or other hardware configuration,
-the state once saved will be OK for every resume afterwards.
-NOTE: The "rckbd restart" command may be different for your
-distribution. Simply replace it with the command you would use to
-set the fonts on screen.