linux-image-5.16.0-6-686 (5.16.18-1) still does not boot on a different machine with the same controller.
Vanilla kernel 5.16.18 built with custom .config for the specific machine fails to boot at the same point too. I'm also trying to track stable patches in the stable tree queue (https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/log/) but it seems to me at the moment there not any patch about ata_pxii in the 5.16.x branch and in the 5.17.x either.
