Documentation/power/userland-swsusp.rst

16 are going to develop your own suspend/resume utilities.
26 assumed to be in the resume mode.  The device cannot be open for simultaneous
49 	from it (0) (after resume the system finds itself finishing the
81 	allocate a swap page from the resume partition
83 	will contain the swap page offset if the call is successful)
90 	set the resume partition and the offset (in <PAGE_SIZE>
94 	containing the resume device specification and the offset); for swap
95 	partitions the offset is always 0, but it is different from zero for
96 	swap files (see Documentation/power/swsusp-and-swap-files.rst for
109 	immediately enter the suspend-to-RAM state, so this call must always
112 	is needed to implement the suspend-to-both mechanism in which the
115 	to resume the system from RAM if there's enough battery power or restore
121 - you cannot read() more than one virtual memory page at a time
122 - read()s across page boundaries are impossible (ie. if you read() 1/2 of
137 snapshot image from/to the kernel will use a swap partition, called the resume
138 partition, or a swap file as storage space (if a swap file is used, the resume
156 SNAPSHOT_ATOMIC_RESTORE will not succeed.  Still, this is not a fool-proof