On 2015?01?06? 21:54, G Gregory wrote:

On 6 January 2015 at 13:50, Hanjun Guo [off-list ref] wrote:

quoted

On 2015?01?06? 19:29, Catalin Marinas wrote:

quoted

On Tue, Jan 06, 2015 at 11:11:07AM +0000, Hanjun Guo wrote:

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On 2015?01?05? 19:05, Catalin Marinas wrote:

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On Sun, Jan 04, 2015 at 09:39:24AM +0000, Hanjun Guo wrote:

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On 2014?12?25? 01:18, Catalin Marinas wrote:
[...]

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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.

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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.

quoted

quoted

+
    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