Re: pmf(9) and Xen domU suspending?

["Jared D. McNeill" <jmcneill%invisible.ca@localhost>]

Jean-Yves Migeon wrote:
> Hi list,
>
> I am working on suspend/resume functionality for port-xen under the 
> supervision of Manuel Bouyer (bouyer@) and Stoned Elipot (seb@). 
> Currently, I am mostly trying to get familiar with NetBSD internals, and 
> Xen.
>
> While studying the code regarding devices relating to port-xen (xenbus, 
> xennet, hypervisor...), I was thinking at how I should implement the 
> suspend/resume mechanisms for theses devices and buses (inspired by ACPI 
> states). Manuel suggested me to have a look at pmf(9), but the 
> documentation tends to be scarce (compared to autoconf machinery on 
> "NetBSD internals"). And since pmf(9) is still a WIP, I am a bit lost 
> with it.
>
> The man page points me to the MI implementation of it in the kernel. 
> However, I would like to know if there lies somewhere some "canonical" 
> example (or how-to) I could read just to get a better understanding of it.
>
> Thanking you in advance for your time and patience,

Hi Jean-Yves --

Take a look at any device driver -- sys/dev/pci/esa.c is a typical example.

In a nutshell: The device's suspend/resume callbacks are responsible for 
stopping and starting the device, and saving/restoring state. The bus 
driver (eg. pci) is typically responsible for power management control 
of those devices. sys/dev/pci/pci.c -- start with the call to 
device_pmf_driver_set_child_register in pciattach.

Cheers,
Jared