On 2015/3/17 13:59, Jon Masters wrote:
On 03/17/2015 12:10 AM, Hanjun Guo wrote:
On 2015/3/17 11:23, Rafael J. Wysocki wrote:
On Tuesday, March 17, 2015 10:36:47 AM Hanjun Guo wrote: Well, almost. There is one problem with that, becuase sleep.c contains code outside of the ACPI_SLEEP-dependent blocks. That code is used for powering off ACPI platforms.
I guess you don't want that code on ARM too, right?
Yes, you are right.
Perhaps we can use ACPI_REDUCED_HARDWARE_ONLY for that? ARM64 will be the
Sorry, I can't fully understand your intention here, could you please explain it more?
Let me guess a little bit. Do you mean use ACPI_REDUCED_HARDWARE_ONLY for powering off ACPI platforms? if so, I guess it's not a good idea, ACPI spec only says that S4BIOS is not supported on HW-reduced ACPI platforms, S5 has no such limitation, if I miss something here, please let me know.
If helpful to the discussion, current SBBR (Server Base Boot Requirements[0]) design guidance is that for power off itself, we will prefer calling an EFI Runtime Service (that will preferentially call an PSCI - ARM Power State Coordination Interface - Secure Monitor Call (SMC
- think SMI-like) internally to perform the shutdown/reboot) for the
action of powering off or resetting 64-bit ARM SBBR platforms.
Agreed, PSCI is the prefer method for power off on ARM64 I think.
Therefore if the alternative of an ACPI-based power off solution were not initially supported, I don't think it would have much practical impact, and it could be addressed after the initial support merged.
I agree. Actually we already removed ACPI power off code for ARM64 in v9 and v10 regardless the ACPI sepc statement about S5, I just want to confirm with Rafael that how to use ACPI_REDUCED_HARDWARE_ONLY properly to do the same thing as we do in v10 (patch - ACPI / sleep: Introduce CONFIG_ACPI_GENERIC_SLEEP), or if we have some other way to do that :)
Thanks Hanjun