Messages in this thread | | | Date | Fri, 14 Jun 2019 23:33:10 +0100 | From | Russell King - ARM Linux admin <> | Subject | Re: [PATCH] ACPI: PM: Export the function acpi_sleep_state_supported() |
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Hi,
On Fri, Jun 14, 2019 at 10:19:02PM +0000, Dexuan Cui wrote: > > -----Original Message----- > > From: Michael Kelley <mikelley@microsoft.com> > > Sent: Friday, June 14, 2019 1:48 PM > > To: Dexuan Cui <decui@microsoft.com>; linux-acpi@vger.kernel.org; > > rjw@rjwysocki.net; lenb@kernel.org; robert.moore@intel.com; > > erik.schmauss@intel.com > > Cc: linux-hyperv@vger.kernel.org; linux-kernel@vger.kernel.org; KY Srinivasan > > <kys@microsoft.com>; Stephen Hemminger <sthemmin@microsoft.com>; > > Haiyang Zhang <haiyangz@microsoft.com>; Sasha Levin > > <Alexander.Levin@microsoft.com>; olaf@aepfle.de; apw@canonical.com; > > jasowang@redhat.com; vkuznets <vkuznets@redhat.com>; > > marcelo.cerri@canonical.com > > Subject: RE: [PATCH] ACPI: PM: Export the function > > acpi_sleep_state_supported() > > > > It seems that sleep.c isn't built when on the ARM64 architecture. Using > > acpi_sleep_state_supported() directly in hv_balloon.c will be problematic > > since hv_balloon.c needs to be architecture independent when the > > Hyper-V ARM64 support is added. If that doesn't change, a per-architecture > > wrapper will be needed to give hv_balloon.c the correct information. This > > may affect whether acpi_sleep_state_supported() needs to be exported vs. > > just removing the "static". I'm not sure what the best approach is. > > > > Michael > > + some ARM experts who worked on arch/arm/kernel/hibernate.c. > > drivers/acpi/sleep.c is only built if ACPI_SYSTEM_POWER_STATES_SUPPORT > is defined, but it looks this option is not defined on ARM. > > It looks ARM does not support the ACPI S4 state, then how do we know > if an ARM host supports hibernation or not?
Don't forget that Linux does not support ACPI on 32-bit ARM, which is quite different from the situation on 64-bit ARM.
arch/arm/kernel/hibernate.c is only for 32-bit ARM, and is written with the assumption that there is no interaction required with any firmware to save state, and later restore state upon resuming.
Or am I missing something?
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