backup of flash #2716
Description
ARTIQ Feature Request
Problem this request addresses
Tests of ARTIQ beta and upgrades between stable releases need flashing. If the existing bitstream is unavailable (forgot to save it somewhere, lost the backup, fear of not being able to reproduce a build, lost access to AFWS etc.) it would be lost. This makes the user reluctant and degrades upgrade experience.
Describe the solution you'd like
We already have read_binary() in artiq_flash. Expose this in the CLI to make a backup of the flash partitions (or of all the flash). This is a sub-optimal because the true size of the used data within the partitions is not known. Consider fine-grained backup of individual partitions vs the entire flash.
Since reading is fast, figure out a way to make this backup by default before any erasing and writing. Timestamp the backups to avoid collisions. Support easy rollback without having to unpack/decipher a (any) backup and/or its implied metadata (partition, device, hardware version). Avoid partition mix-up when restoring.
Additional context
Could encourage more widespread testing of experimental features, debugging in production environments, migration away from outdated stable releases.