From mboxrd@z Thu Jan 1 00:00:00 1970 From: hanjun.guo@linaro.org (Hanjun Guo) Date: Tue, 06 Jan 2015 21:59:41 +0800 Subject: [PATCH v5 18/18] Documentation: ACPI for ARM64 In-Reply-To: References: <1413553034-20956-1-git-send-email-hanjun.guo@linaro.org> <1413553034-20956-19-git-send-email-hanjun.guo@linaro.org> <20141224171815.GD13399@e104818-lin.cambridge.arm.com> <54A90A4C.60908@linaro.org> <20150105110533.GA14967@e104818-lin.cambridge.arm.com> <54ABC2CB.6@linaro.org> <20150106112929.GB8829@e104818-lin.cambridge.arm.com> <54ABE82E.30308@linaro.org> Message-ID: <54ABEA4D.9020103@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 2015?01?06? 21:54, G Gregory wrote: > On 6 January 2015 at 13:50, Hanjun Guo wrote: >> On 2015?01?06? 19:29, Catalin Marinas wrote: >>> >>> On Tue, Jan 06, 2015 at 11:11:07AM +0000, Hanjun Guo wrote: >>>> >>>> On 2015?01?05? 19:05, Catalin Marinas wrote: >>>>> >>>>> On Sun, Jan 04, 2015 at 09:39:24AM +0000, Hanjun Guo wrote: >>>>>> >>>>>> On 2014?12?25? 01:18, Catalin Marinas wrote: >>>>>> [...] >>>>>>> >>>>>>> >>>>>>> In addition to the above and _DSD requirements/banning, I would also >>>>>>> add >>>>>>> some clear statements around: >>>>>>> >>>>>>> _OSC: only global/published capabilities are allowed. For >>>>>>> device-specific _OSC we need a process or maybe we can ban them >>>>>>> entirely >>>>>>> and rely on _DSD once we clarify the process. >>>>>>> >>>>>>> _OSI: firmware must not check for certain _OSI strings. Here I'm not >>>>>>> sure what we would have to do for ARM Linux. Reporting "Windows" does >>>>>>> not make any sense but not reporting anything can, as Matthew Garrett >>>>>>> pointed out, can be interpreted by firmware as "Linux". In addition to >>>>>>> any statements in this document, I suggest you patch >>>>>>> drivers/acpi/acpica/utosi.c accordingly, maybe report "Linux" for ARM >>>>>>> and print a kernel warning so that we notice earlier. >>>>>>> >>>>>>> ACPI_OS_NAME: this is globally defined as "Microsoft Windows NT". It >>>>>>> doesn't make much sense in the ARM context. Could we change it to >>>>>>> "Linux" when CONFIG_ARM64? >>>> >>>> >>>> I think we can introduce a Kconfig such as CONFIG_ACPI_OS_NAME_LINUX, >>>> selected by ARM64 and change ACPI_OS_NAME to "Linux" when >>>> CONFIG_ACPI_OS_NAME_LINUX defined. (we can not add CONFIG_ARM64 in >>>> ACPICA code directly since it will be used by windows too) >>>> >>>> some code like below: >>> >>> >>> This looks fine for me (with some minor comments below) but I'm not an >>> ACPI expert to say there wouldn't be any issues. >>> >>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>>> index b1f9a20..de567a3 100644 >>>> --- a/arch/arm64/Kconfig >>>> +++ b/arch/arm64/Kconfig >>>> @@ -1,5 +1,6 @@ >>>> config ARM64 >>>> def_bool y >>>> + select ACPI_OS_NAME_LINUX if ACPI >>>> select ARCH_BINFMT_ELF_RANDOMIZE_PIE >>>> select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE >>>> select ARCH_HAS_GCOV_PROFILE_ALL >>>> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig >>>> index 8951cef..11a10ac 100644 >>>> --- a/drivers/acpi/Kconfig >>>> +++ b/drivers/acpi/Kconfig >>>> @@ -369,6 +369,10 @@ config ACPI_REDUCED_HARDWARE_ONLY >>>> >>>> If you are unsure what to do, do not enable this option. >>>> >>>> +config ACPI_OS_NAME_LINUX >>>> + bool "Using Linux for _OS method" if EXPERT >>>> + def_bool n >>> >>> >>> No need for a default n, it is off by default. Alternatively you could >>> say: >>> >>> default y if ARM64 >> >> >> ok. >> >>> >>>> + >>>> source "drivers/acpi/apei/Kconfig" >>>> >>>> config ACPI_EXTLOG >>>> diff --git a/include/acpi/acconfig.h b/include/acpi/acconfig.h >>>> index 5a0a3e5..db5e13e 100644 >>>> --- a/include/acpi/acconfig.h >>>> +++ b/include/acpi/acconfig.h >>>> @@ -69,7 +69,11 @@ >>>> * code that will not execute the _OSI method unless _OS matches the >>>> string >>>> * below. Therefore, change this string at your own risk. >>>> */ >>>> +#ifndef ACPI_OS_NAME_USING_LINUX >>>> #define ACPI_OS_NAME "Microsoft Windows NT" >>>> +#else >>>> +#define ACPI_OS_NAME "Linux" >>>> +#endif >>> >>> >>> Can you not use CONFIG_ACPI_OS_NAME_LINUX directly here without >>> introducing another macro? >> >> >> acconfig.h is part of ACPICA core and will be shared by windows and >> other OS, so use CONFIG from Linux in this file is not allowed I think. >> > > We could just propse > #ifndef ACPI_OS_NAME > #define ACPI_OS_NAME "Microsoft Windows NT" > #endif > > to acpica maintainers. This will not alter Windows or other software usage > but we can then override it in Linux when/if we want to. this is better and looks great to me :) Thanks Hanjun