On 2015年01月06日 19:29, Catalin Marinas wrote:
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
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 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?
I'm not sure, I will check it and get back when I have the answer.
Thanks
Hanjun
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