Hi all, My name is Tony and I've been researching/developing using Xen for potential upcoming uses in our embedded systems. I started with Xen using Xilinx tools about a year ago and still have lots to learn about what it can to do in the embedded space. So far, I've managed to integrate Xen and Linux into an existing product that exclusively runs bare-metal code on a ZynqMP SoC and migrate some of the functionality into custom Linux driver/userspace.
I'm now looking at low power support, for now at least between Xen (4.16) and Linux (5.15) dom0. I've tried a few different Linux kernel configs around power management and each time I try to suspend from linux dom0 (via sysfs or systemctl), Xen will watchdog on dom0 guest. AFAIK, Xen should trap on a 'WFI' from guests, but from what I can tell debugging through the linux suspend process is it's spinning in a 'suspend-to-idle' loop before it can get to issuing a 'WFI' or using PSCI interface to notify Xen. I'm beginning to suspect that 'low power' support for embedded arm64 just isn't quite there yet, or am I missing something in the configs? I realize this could very well be a Linux 'issue' but checking here first. I know Xen presents a flattened device tree to Linux without CPU idle-state nodes and maybe this is causing the linux guest to only do the suspend-to-idle mode? I should mention that I'm booting up using dom0less feature if that matters. Appreciate the help, thanks. CONFIDENTIALITY NOTICE: This e-mail, including any attachments, may contain information that is confidential and privileged. Any unauthorized disclosure, reproduction or use of this e-mail is prohibited. If you are not the intended recipient, please notify the sender by reply e-mail or telephone and permanently delete this e-mail and any reproductions immediately.
