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Commit 35506467 authored by Mario Limonciello's avatar Mario Limonciello Committed by Rafael J. Wysocki
Browse files

PM / hibernate: Make passing hibernate offsets more friendly 



Currently the only way to specify a hibernate offset for a
swap file is on the kernel command line.

Add a new /sys/power/resume_offset that lets userspace
specify the offset and disk to use when initiating a hibernate
cycle.

Signed-off-by: default avatarMario Limonciello <mario.limonciello@dell.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent dbdd0f58

Documentation/ABI/testing/sysfs-power

+14 −0
Original line number Diff line number Diff line
@@ -287,3 +287,17 @@ Description: 
		Writing a "1" to this file enables the debug messages and

		writing a "0" (default) to it disables them.  Reads from

		this file return the current value.



What:		/sys/power/resume_offset

Date:		April 2018

Contact:	Mario Limonciello <mario.limonciello@dell.com>

Description:

		This file is used for telling the kernel an offset into a disk

		to use when hibernating the system such as with a swap file.



		Reads from this file will display the current offset

		the kernel will be using on the next hibernation

		attempt.



		Using this sysfs file will override any values that were

		set using the kernel command line for disk offset.
 
 No newline at end of file

Documentation/power/swsusp.txt

+9 −1
Original line number Diff line number Diff line
@@ -24,8 +24,16 @@ Some warnings, first. 
 * see the FAQ below for details.  (This is not true for more traditional

 * power states like "standby", which normally don't turn USB off.)



Swap partition:

You need to append resume=/dev/your_swap_partition to kernel command

line. Then you suspend by

line or specify it using /sys/power/resume.



Swap file:

If using a swapfile you can also specify a resume offset using

resume_offset=<number> on the kernel command line or specify it

in /sys/power/resume_offset.



After preparing then you suspend by



echo shutdown > /sys/power/disk; echo disk > /sys/power/state

kernel/power/hibernate.c

+24 −0
Original line number Diff line number Diff line
@@ -1061,6 +1061,29 @@ static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr, 


power_attr(resume);



static ssize_t resume_offset_show(struct kobject *kobj,

				  struct kobj_attribute *attr, char *buf)

{

	return sprintf(buf, "%llu\n", (unsigned long long)swsusp_resume_block);

}



static ssize_t resume_offset_store(struct kobject *kobj,

				   struct kobj_attribute *attr, const char *buf,

				   size_t n)

{

	unsigned long long offset;

	int rc;



	rc = kstrtoull(buf, 0, &offset);

	if (rc)

		return rc;

	swsusp_resume_block = offset;



	return n;

}



power_attr(resume_offset);



static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,

			       char *buf)

{
@@ -1106,6 +1129,7 @@ power_attr(reserved_size); 


static struct attribute * g[] = {

	&disk_attr.attr,

	&resume_offset_attr.attr,

	&resume_attr.attr,

	&image_size_attr.attr,

	&reserved_size_attr.attr,