Hi, On Fri, Jun 14, 2019 at 10:19:02PM +0000, Dexuan Cui wrote: > > -----Original Message----- > > From: Michael Kelley <mikel...@microsoft.com> > > Sent: Friday, June 14, 2019 1:48 PM > > To: Dexuan Cui <de...@microsoft.com>; linux-a...@vger.kernel.org; > > r...@rjwysocki.net; l...@kernel.org; robert.mo...@intel.com; > > erik.schma...@intel.com > > Cc: linux-hyp...@vger.kernel.org; linux-kernel@vger.kernel.org; KY > > Srinivasan > > <k...@microsoft.com>; Stephen Hemminger <sthem...@microsoft.com>; > > Haiyang Zhang <haiya...@microsoft.com>; Sasha Levin > > <alexander.le...@microsoft.com>; o...@aepfle.de; a...@canonical.com; > > jasow...@redhat.com; vkuznets <vkuzn...@redhat.com>; > > marcelo.ce...@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? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
