[Pm-utils] [RFC] Writing "${HIBERNATE_MODE}" unconditionally to /sys/power/disk

[Michael Biebl]

2008/4/28 Stefan Seyfried <seife at suse.de>:
> Michael Biebl wrote:
>  > Hi,
>  >
>  > please see http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=450515
>  > for the background.
>  >
>  > Apparently, writing "platform" unconditionally to /sys/power/disk can
>  > lead to suspend failures, if this method is not supported.
>
>  Well, this needs to be fixed in the kernel.

Unless the kernel is fixed, we have to workaround this somehow.

>
>
>  > If I read the kernel documentation correctly [1], "firmware" or
>  > "platform" can be not supported on certain platforms. The way to
>  > detect that, is probably to grep for it in /sys/power/disk. The
>  > documentation is not clear about that.
>
>  I do not believe that "firmware" still exists (this was the old s4bios code
>  that never worked on more than one machine)
>

ok.

>
>  > So the question: Should we generally check for HIBERNATE_MODE first:
>
>  I don't think so. The kernel should just fall back to a sane default of
>  "shutdown" if platform is not supported.
>  And indeed, i get a "write error: invalid argument" if i try to echo platform
>  into /sys/power/disk in qemu-kvm (where platform is not supported).

Ok, so we should notify the kernel hackers about this (who is the
right contact for this, Rafael?)

As long as we don't have such support in the kernel, checking for
HIBERNATE_METHOD seems to be the best compromise to me.

Cheers,
Michael

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