On Tue, Jan 06, 2015 at 11:11:07AM +0000, Hanjun Guo wrote: > On 2015年01月05日 19:05, Catalin Marinas wrote: > > On Sun, Jan 04, 2015 at 09:39:24AM +0000, Hanjun Guo wrote: > >> On 2014年12月25日 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 > + > 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? > >> We will work on this both on ASWG and linux ACPI driver side, as Dong > >> and Charles pointed out, _OSI things can be solved in ACPI spec, when > >> that is done, we can modify the kernel driver to fix the problems above. > > > > Which driver? > > the ACPICA core driver as you suggested, sorry for the confusion. > > > What about ACPI_OS_NAME? Would you suggest it is fine to report > > "Microsoft Windows NT" on an ARM system? That _OS_ not _OSI. > > No, not at all. I prefer "Linux" > In include/acpi/acconfig.h, when ACPI_OS_NAME defined, it says: > "OS name, used for the _OS object. The _OS object is essentially > obsolete,..." > for some legacy reasons, we needed "Microsoft Windows NT", but ACPI > for ARM64 on linux is totally new, I think we can change it to > "Linux" when CONFIG_ARM64 as you suggested. We could ignore this change for now if we don't expect the _OS object to be used at all. But do we have any other way to check the AML code for this? Would FWTS catch such obsolete cases? -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
