X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=Documentation%2Fpower%2Fswsusp.txt;h=b28b7f04abb8022a75bb6646c544212562a9c754;hb=987b0145d94eecf292d8b301228356f44611ab7c;hp=d7814a113ee1752a7c91c54ae6841407baa73370;hpb=f7ed79d23a47594e7834d66a8f14449796d4f3e6;p=linux-2.6.git diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt index d7814a113..b28b7f04a 100644 --- a/Documentation/power/swsusp.txt +++ b/Documentation/power/swsusp.txt @@ -17,11 +17,6 @@ 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 @@ -32,18 +27,19 @@ 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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -337,37 +333,4 @@ init=/bin/bash, then swapon and starting suspend sequence manually usually does the trick. Then it is good idea to try with latest vanilla kernel. -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 -data. - -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 -with "sync"? - -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.