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Message-ID: <54C277B4.4090808@redhat.com> Date: Fri, 23 Jan 2015 09:32:52 -0700 From: Al Stone <ahs3@...hat.com> To: "Rafael J. Wysocki" <rjw@...ysocki.net>, al.stone@...aro.org CC: tony.luck@...el.com, fenghua.yu@...el.com, catalin.marinas@....com, will.deacon@....com, tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, lenb@...nel.org, robert.moore@...el.com, linux-ia64@...r.kernel.org, linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, devel@...ica.org, linaro-acpi@...ts.linaro.org, linaro-kernel@...ts.linaro.org, patches@...aro.org Subject: Re: [PATCH 0/7] Start deprecating _OSI on new architectures On 01/23/2015 08:43 AM, Rafael J. Wysocki wrote: > Hi Al, > > On Thursday, January 22, 2015 05:44:37 PM al.stone@...aro.org wrote: >> From: Al Stone <al.stone@...aro.org> >> >> The use of the ACPI _OSI method in Linux has a long and sordid history. >> Instead of perpetuating past complications on new architectures, the >> consensus amongst those writing the ACPI specification and those using >> it seems to be to ultimately deprecate the use of _OSI. I plan to >> propose such a change to the ACPI specification in the near future. >> >> In the meantime, these patches rearrange the implementation of _OSI so >> that it can be deprecated, or ultimately removed completely, on at least >> arm64 platforms. This is done by simply moving the functions implementing >> _OSI to arch-dependent locations. For x86, there should be no change >> in functionality. For ia64, while it does duplicate some code from x86, >> there is no longer any connection to the ACPI blacklist code that is only >> used by x86. For arm64, any use of the _OSI method generates a warning >> that it has been deprecated, and then always returns false; i.e., that >> the capability being queried for, whether OS name or functionality, is >> not supported. This is the first six of the patches. > > While I seem to understand the motivation, I don't really like moving code > around, especially in the ia64 area where we have limited means to test the > changes. And I hate code duplication pretty much in any form. I'm not too wild about it either, but it seemed to avoid #ifdefs when I was trying to think it through. > Also I don't see anything wrong with sharing code between x86 and ia64 like > we do today. Fair enough. That's entirely up to you; the only reason I saw for separating them was removing the one call to check the blacklist on ia64. That would have a tiny time savings at boot time, but it is definitely down in the noise level. > So, why don't you move the _OSI handling out of osl.c into a separate file > that will only build if something like CONFIG_ARCH_SPECIFIC_ACPI_OSI is not > set (and same for blacklist.c). Then, you'll only need to make ARM64 > set CONFIG_ARCH_SPECIFIC_ACPI_OSI and provide the necessary functions > and you can leave the other architectures alone. > > Does that make sense to you? It does. I'll rewrite these based on that approach. Definitely a lot less code motion involved... >> The final patch changes the default value for the _OS_ method for arm64 >> only. Since there is no need to pretend to be older versions of Windows, >> or any other OS at all, the _OS_ method will return "Linux" on arm64. >> One can still use the acpi_os_name kernel parameter if there is a need >> to use some other value. >> >> Since we are breaking apart code previously shared, I have tried to make >> it so that applying the x86 patches alone will continue to compile, at >> the expense of breaking the build on non-x86 platforms. However, once >> all of the patches are applied, we should be able to compile on all three >> architectures. It is best to treat these as one whole. >> >> I have only done simple testing with these patches on arm64 and x86 (AMD >> Seattle and a Lenovo t440s ThinkPad, respectively). Things seem to work >> as they should once booted, but this is a very, very small sample of >> possible machines. The ia64 patches cross-compile, but I personally have >> no way to test them. >> >> The arm64 patches also rely on having applied Hanjun's patches for ACPI 5.1 >> on arm64 [0]. The x86 and ia64 parts are not dependent on that patch set, >> though, and should be usable independently (i.e., patches 1, 3, 4 and 6). >> >> NB: some of the patches do not pass checkpatch.pl; the failures I saw were >> all part of the original code but are only showing up because that code is >> changing location, so I have left them as is. If necessary, they could be >> fixed but I was more concerned about the number of changes needed on ia64 >> and not having any way to test them. >> >> >> [0] https://lkml.org/lkml/2015/1/14/586 >> >> >> Al Stone (6): >> ia64: ACPI: move kernel acpi files to a directory >> arm64: ACPI: move kernel acpi files to a directory >> x86: ACPI: create arch-dependent version of acpi_osi_handler() >> ia64: ACPI: create arch-dependent version of acpi_osi_handler() >> arm64: ACPI: create arch-dependent version of acpi_osi_handler() >> x86: ia64: arm64: ACPI: move _OSI support functions to arch-dependent >> locations >> >> Hanjun Guo (1): >> ACPI: use Linux as ACPI_OS_NAME for _OS on ARM64 >> >> arch/arm64/Kconfig | 1 + >> arch/arm64/kernel/Makefile | 2 +- >> arch/arm64/kernel/acpi.c | 359 -------------- >> arch/arm64/kernel/acpi/Makefile | 1 + >> arch/arm64/kernel/acpi/acpi.c | 359 ++++++++++++++ >> arch/arm64/kernel/acpi/osi.c | 26 + >> arch/ia64/kernel/Makefile | 2 +- >> arch/ia64/kernel/acpi-ext.c | 104 ---- >> arch/ia64/kernel/acpi.c | 1000 -------------------------------------- >> arch/ia64/kernel/acpi/Makefile | 1 + >> arch/ia64/kernel/acpi/acpi-ext.c | 104 ++++ >> arch/ia64/kernel/acpi/acpi.c | 1000 ++++++++++++++++++++++++++++++++++++++ >> arch/ia64/kernel/acpi/osi.c | 119 +++++ >> arch/x86/kernel/acpi/Makefile | 2 +- >> arch/x86/kernel/acpi/blacklist.c | 327 +++++++++++++ >> arch/x86/kernel/acpi/boot.c | 5 +- >> arch/x86/kernel/acpi/osi.c | 255 ++++++++++ >> drivers/acpi/Kconfig | 8 + >> drivers/acpi/Makefile | 1 - >> drivers/acpi/blacklist.c | 323 ------------ >> drivers/acpi/osl.c | 217 --------- >> include/acpi/acconfig.h | 2 + >> include/acpi/platform/aclinux.h | 4 + >> include/linux/acpi.h | 4 +- >> 24 files changed, 2215 insertions(+), 2011 deletions(-) >> delete mode 100644 arch/arm64/kernel/acpi.c >> create mode 100644 arch/arm64/kernel/acpi/Makefile >> create mode 100644 arch/arm64/kernel/acpi/acpi.c >> create mode 100644 arch/arm64/kernel/acpi/osi.c >> delete mode 100644 arch/ia64/kernel/acpi-ext.c >> delete mode 100644 arch/ia64/kernel/acpi.c >> create mode 100644 arch/ia64/kernel/acpi/Makefile >> create mode 100644 arch/ia64/kernel/acpi/acpi-ext.c >> create mode 100644 arch/ia64/kernel/acpi/acpi.c >> create mode 100644 arch/ia64/kernel/acpi/osi.c >> create mode 100644 arch/x86/kernel/acpi/blacklist.c >> create mode 100644 arch/x86/kernel/acpi/osi.c >> delete mode 100644 drivers/acpi/blacklist.c >> >> > -- ciao, al ----------------------------------- Al Stone Software Engineer Red Hat, Inc. ahs3@...hat.com ----------------------------------- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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