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What I understand is that recovery-from-boot.p and install-recovery.sh will try to reload the recovery each times the phone boot ... If we remove those files, no more restore of the recovery?
Thanks ...
Yes, those two files (which are on a stock ROM only) check, on every boot, to see if you have a stock recovery, and if not, restore the stock recovery. If you remove or rename them, whatever recovery you currently have will remain. To get the stock recovery back, you just have to rename them back to their original names, reboot, and presto, stock recovery again.
As well, every time you flash an official, signed update from Google, it will always add those two files to you ROM, so you will have to delete them after every official update before rebooting (after flashing a custom recovery).