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If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> |
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| .. | ||
| regulator | ||
| 00-INDEX | ||
| apm-acpi.txt | ||
| basic-pm-debugging.txt | ||
| devices.txt | ||
| drivers-testing.txt | ||
| freezing-of-tasks.txt | ||
| interface.txt | ||
| notifiers.txt | ||
| opp.txt | ||
| pci.txt | ||
| pm_qos_interface.txt | ||
| power_supply_class.txt | ||
| runtime_pm.txt | ||
| s2ram.txt | ||
| states.txt | ||
| swsusp-and-swap-files.txt | ||
| swsusp-dmcrypt.txt | ||
| swsusp.txt | ||
| tricks.txt | ||
| userland-swsusp.txt | ||
| video_extension.txt | ||
| video.txt | ||