topic Re: IMX8MP Android Hibernate in i.MX Processors

IMX8MP Android Hibernate

persandberg — Fri, 31 Jan 2025 09:11:03 GMT

Have someone tried to hibernate with suspend-to-disk on Android13/14 and got it working?

The system is build with Kernel config paramters as follow:

CONFIG_SUSPEND=y
CONFIG_SUSPEND_FREEZER=y
CONFIG_HIBERNATE_CALLBACKS=y
CONFIG_HIBERNATION=y
CONFIG_HIBERNATION_SNAPSHOT_DEV=y
CONFIG_PM_STD_PARTITION="/dev/block/mmcblk2p14"
CONFIG_PM_SLEEP=y
CONFIG_PM_SLEEP_SMP=y
CONFIG_ARCH_HIBERNATION_POSSIBLE=y
CONFIG_ARCH_HIBERNATION_HEADER=y
CONFIG_ARCH_SUSPEND_POSSIBLE=y

The error we get is:

[ 1039.323435] PM: hibernation: Creating image:
[ 1039.323435] PM: hibernation: Need to copy 179787 pages
[ 1039.323435] PM: hibernation: Normal pages needed: 179787 + 1024, available pages: 270631
[ 1039.323435] PM: hibernation: Memory allocation failed
[ 1039.323435] PM: hibernation: Error -12 creating image

Re: IMX8MP Android Hibernate

jamesbone — Fri, 31 Jan 2025 16:26:42 GMT

Which board are you using? to test? Since there is some dependency to the PMIC of the board to get the Hibernation available.

Re: IMX8MP Android Hibernate

persandberg — Wed, 05 Feb 2025 06:55:36 GMT

We are using Technexion Wandboard EDM-G-IMX8MP. It uses the NXP PMIC PCA9450C.

Our problems start with memory allocations for hibernation images. We suspect this is prior to stopping/starting the PMIC.

We are currently executing on Android 13 where we have made a swap partition:

total used free shared buffers

Mem: 1.6G 808M 857M 584K 708K

-/+ buffers/cache: 807M 858M

Swap: 6.0G 473M 5.5G

Swap is allocated from a dedicated swap partition residing on disk (eMMC).

When we hibernate the system, it seems we are running out of memory. However, we should have enough. What could be the problem?

Re: IMX8MP Android Hibernate

jamesbone — Fri, 07 Feb 2025 18:33:20 GMT

File system inconsistency

Hibernation requires user create the hibernation image each time. The hibernation image stores memory information and can restore system then. File system has the inode and the related information also in the memory so it will be stored with hibernation images. This is good for most of PC, NB. But it is not practical for most embedded system. We would like to create hibernation image once and always restore system from the image. It's so call Single Image mode. On my approach, I tried to use ram disk as Android System partition. The ram disk will be part of hibernation and then we can restore from system using the same image every time.