diff options
Diffstat (limited to 'Documentation/power/swsusp.txt')
| -rw-r--r-- | Documentation/power/swsusp.txt | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt index 9d60ab717a7..f732a8321e8 100644 --- a/Documentation/power/swsusp.txt +++ b/Documentation/power/swsusp.txt @@ -33,6 +33,11 @@ echo shutdown > /sys/power/disk; echo disk > /sys/power/state echo platform > /sys/power/disk; echo disk > /sys/power/state +. If you would like to write hibernation image to swap and then suspend +to RAM (provided your platform supports it), you can try + +echo suspend > /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 @@ -45,10 +50,23 @@ echo N > /sys/power/image_size before suspend (it is limited to 500 MB by default). +. The resume process checks for the presence of the resume device, +if found, it then checks the contents for the hibernation image signature. +If both are found, it resumes the hibernation image. + +. The resume process may be triggered in two ways: + 1) During lateinit: If resume=/dev/your_swap_partition is specified on + the kernel command line, lateinit runs the resume process. If the + resume device has not been probed yet, the resume process fails and + bootup continues. + 2) Manually from an initrd or initramfs: May be run from + the init script by using the /sys/power/resume file. It is vital + that this be done prior to remounting any filesystems (even as + read-only) otherwise data may be corrupted. Article about goals and implementation of Software Suspend for Linux ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Author: Gábor Kuti +Author: Gábor Kuti Last revised: 2003-10-20 by Pavel Machek Idea and goals to achieve @@ -66,7 +84,8 @@ swsusp saves the state of the machine into active swaps and then reboots or powerdowns. You must explicitly specify the swap partition to resume from with ``resume='' kernel option. If signature is found it loads and restores saved state. If the option ``noresume'' is specified as a boot parameter, it skips -the resuming. +the resuming. If the option ``hibernate=nocompress'' is specified as a boot +parameter, it saves hibernation image without compression. In the meantime while the system is suspended you should not add/remove any of the hardware, write to the filesystems, etc. @@ -191,7 +210,7 @@ Q: There don't seem to be any generally useful behavioral distinctions between SUSPEND and FREEZE. A: Doing SUSPEND when you are asked to do FREEZE is always correct, -but it may be unneccessarily slow. If you want your driver to stay simple, +but it may be unnecessarily slow. If you want your driver to stay simple, slowness may not matter to you. It can always be fixed later. For devices like disk it does matter, you do not want to spindown for @@ -201,7 +220,10 @@ Q: After resuming, system is paging heavily, leading to very bad interactivity. A: Try running -cat `cat /proc/[0-9]*/maps | grep / | sed 's:.* /:/:' | sort -u` > /dev/null +cat /proc/[0-9]*/maps | grep / | sed 's:.* /:/:' | sort -u | while read file +do + test -f "$file" && cat "$file" > /dev/null +done after resume. swapoff -a; swapon -a may also be useful. @@ -236,7 +258,7 @@ disk. Whole sequence goes like running system, user asks for suspend-to-disk - user processes are stopped (in common case there are none, but with resume-from-initrd, noone knows) + user processes are stopped (in common case there are none, but with resume-from-initrd, no one knows) read image from disk @@ -320,7 +342,7 @@ 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 +/sys/power/resume file from initrd. Be sure not to mount anything, not even read-only mount, or you are going to lose your data. |