On Tue, Aug 01, 2006 at 09:03:32PM +0200, Norbert Schuch wrote:
> Hi,
> 
> [problem summary: system hangs at "Restarting tasks" when suspending with 
> powersave, but not with hibernate or "echo disk > /sys/power/state"]
> 
> latest update: I played around a bit with thaw_processes() in 
> power/process.c, and the system hangs during the final call of schedule() 
> in that function. (However, I figured out that schedule() is a bit too 
> large for me...).

Well, if i understand this stuff correctly (which i am not sure about ;-)
the thaw_process() stuff basically just sets the "i can run again" flag for
a process, so it is very well possible that the schedule() call is the one
that _really_ starts the processes, so they will not run until then. (they
will only get cpu time from the scheduler once schedule() is called).

I am still thinking about what we do different from hibernate or just plain
manually invoking suspend...
The only thing i can imagine being the problem is that we switch off the
machine after suspend in "platform" mode (means: through the ACPI bios)
instead of the default "shutdown" mode (means: like a "normal" shutdown
does).

So does it work if you change SUSPEND2DISK_SHUTDOWN_MODE to "shutdown" in
/etc/powersave/sleep?

If this helps, it should also fail when invoked manually, if you
do "echo platform > /sys/power/disk; echo disk > /sys/power/state".

We are using platform mode since this is generally "the right thing" to do,
according to the ACPI spec. However, we are a bit more vulnerable to strange
interactions of the BIOS and kernel, be it BIOS bugs or kernel bugs, we do
not really know.

The problem is: some machines break with "shutdown", some break with
"platform". There is no universal "do the right thing" setting :-(

If this is not the culprit, i really have no idea how to debug this
further.
-- 
Stefan Seyfried                     | "Please, just tell people
QA / R&D Team Mobile Devices        |               to use KDE."
SUSE LINUX Products GmbH, Nürnberg  |          -- Linus Torvalds
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