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Allwinner Continues Work On Linux Patches To Dump Kernel Errors To Block Devices
For the better part of a decade there has been the Linux kernel pstore implementation for access to persistent storage that can survive reboots that could log information in the system's "dying moments" with the dmesg log or MCE data in the case of show-stopping problems, but this obviously requires the system to have exposed some persistent storage dedicated for this task. With newer x86_64 hardware there is Linux Pstore support with flash memory and ACPI ESRT standard, but less so in the ARM/embedded space. Especially with these embedded devices often lacking any batteries, the options for storing any crash data to survive reboots is much more limited.
Allwinner Tech has been working for a while on pstore_block to allow dumping logs to block devices rather than any persistent RAM. In its current form this allows dumping the kernel dmesg output to a standard block device like a partition on eMMC memory on ARM boards. The block partition will be treated as a circular buffer for records that can then be read back at a later point.
The sixth version of these kernel patches were published today. Those interested in learning more about this "PSTORE_BLK" option can find the current proposal on the kernel mailing list.