Xen devel - Jul 2013 - Re: [PATCH v4 0/5] Xen/ACPI: support sleep state entering on hardware reduced systems

On Saturday, July 27, 2013 03:33:31 PM Ben Guthro wrote:
> 
> On Jul 27, 2013, at 9:51 AM, "Rafael J. Wysocki"
<rjw@sisk.pl> wrote:
> 
> > On Thursday, June 27, 2013 11:01:58 AM Ben Guthro wrote:
> >> In version 3.4 acpi_os_prepare_sleep() got introduced in parallel
with
> >> reduced hardware sleep support, and the two changes
didn''t get
> >> synchronized: The new code doesn''t call the hook function
(if so
> >> requested). Fix this, requiring a boolean parameter to be added to
the
> >> hook function to distinguish "extended" from
"legacy" sleep.
> >> 
> >> This requires adjusting TXT, but the adjustments only go as far as
> >> failing the extended mode call (since, looking at the TXT
interface,
> >> there doesn''t even appear to be precautions to deal with
that
> >> alternative interface).
> >> 
> >> The hypervisor change underlying this is commit 62d1a69
("ACPI: support
> >> v5 (reduced HW) sleep interface") on the master branch of
> >> git://xenbits.xen.org/xen.git.
> >> 
> >> Signed-off-by: Ben Guthro <benjamin.guthro@citrix.com>
> >> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> >> Cc: Richard L Maliszewski <richard.l.maliszewski@intel.com>
> >> Cc: Gang Wei <gang.wei@intel.com>
> >> Cc: Shane Wang <shane.wang@intel.com>
> >> Cc: Bob Moore <robert.moore@intel.com>
> >> Cc: Rafaell J. Wysocki <rjw@sisk.pl>
> >> Cc: linux-acpi@vger.kernel.org
> >> Cc: tboot-devel@lists.sourceforge.net 
> >> 
> >> v2: Extend description to include reference to hypervisor side
change
> >> v3: Split into multiple patches, separating subsystems
> >>    Remove bool parameters, in favor of u8
> >> v4: Remove linux/acpi.h dependencies
> >>    Further patch split to break out acpica from OSL
> >>    More bool vs u8 fixes
> >> 
> >> Ben Guthro (5):
> >>  acpi: Remove need to include linux/acpi.h in common acpica code
> >>  acpi: Call acpi_os_prepare_sleep hook in reduced hardware sleep
path
> >>  acpi: Adjust linux acpi OS functions to new extended parameter
> >>  x86/tboot: Fail extended mode reduced hardware sleep
> >>  xen/acpi: notify xen when reduced hardware sleep is available
> > 
> > The ongoing discussion means to me that the ACPICA maintainers
don''t want
> > acpi_os_prepare_sleep() and quite frankly I understand them, because
ACPICA
> > is about implementing the spec and not about things beyond it.
> > 
> > This means that patch [1/5] goes away.
> > 
> > That said, at the same time we need to address the problem at hand,
which
> > is to make Xen work with the reduced HW sleep.
> > 
> > For that, I don''t honestly think that modifying
acpi_os_prepare_sleep() the
> > way the patchset is doing it is appropriate and the change of the
meaning of
> > the arguments is simply disgusting.
> > 
> > To me, it would be much cleaner to add
acpi_os_prepare_extended_sleep()
> > specifically to be called by acpi_hw_extended_sleep() and make tboot
and Xen
> > use that.
> > 
> > This way or another, we''ll need to live with one more
divergence between the
> > upstream ACPICA and the Linux ACPICA code because of that, but
that''d be just
> > a few added lines in acpi_hw_extended_sleep(), so I suppose it
wouldn''t be
> > such a big deal.
> > 
> 
> Ok, thank you for the review, and being open to addressing the problem at
> hand,
No problem, although I''m not exactly happy with it.
> without a full architecture rework (not to say that that discussion is not
> also needed)
Sure, it is needed.
> I will try to make some time next week to rework the patch set to address
> these concerns, and submit a new series. 
Thanks!

Rafael