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authorPavel Machek <pavel@ucw.cz>2010-04-23 20:32:29 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2010-05-10 23:08:17 +0200
commitbc6a0cbd576c66995d782331456f68ae63a50af4 (patch)
tree0889b8fb0c8d775e32daf179a2a2c5ca9441120c /Documentation/power
parentc92445fadb9179d811b5cb044947ad4712403541 (diff)
PM / Hibernate: document open(/dev/snapshot) side effects
Opening and closing /dev/snapshot causes the kernel to carry out some hibernate preparations that should be documented. [rjw: Added the changelog.] Signed-off-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'Documentation/power')
-rw-r--r--Documentation/power/userland-swsusp.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/power/userland-swsusp.txt b/Documentation/power/userland-swsusp.txt
index b967cd9137d..81680f9f590 100644
--- a/Documentation/power/userland-swsusp.txt
+++ b/Documentation/power/userland-swsusp.txt
@@ -24,6 +24,10 @@ assumed to be in the resume mode. The device cannot be open for simultaneous
reading and writing. It is also impossible to have the device open more than
once at a time.
+Even opening the device has side effects. Data structures are
+allocated, and PM_HIBERNATION_PREPARE / PM_RESTORE_PREPARE chains are
+called.
+
The ioctl() commands recognized by the device are:
SNAPSHOT_FREEZE - freeze user space processes (the current process is