diff mbox

[v2,1/5] ACPI: move acpi_os_handler() so it can be made arch-dependent later

Message ID 1423009304-5007-2-git-send-email-al.stone@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

al.stone@linaro.org Feb. 4, 2015, 12:21 a.m. UTC
From: Al Stone <al.stone@linaro.org>

In order to deprecate the use of _OSI for arm64 or other new architectures,
we need to make the default handler something we can change for various
platforms.  This patch moves the definition of acpi_osi_handler() -- the
function used by ACPICA as a callback for evaluating _OSI -- into a separate
file.  Subsequent patches will change which files get built so that we can
then build the version of _OSI we need for a particular architecture.

There is no functional change.

Signed-off-by: Al Stone <al.stone@linaro.org>
---
 drivers/acpi/Makefile |   2 +-
 drivers/acpi/osi.c    | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/acpi/osl.c    |  24 ------------
 include/linux/acpi.h  |   1 +
 4 files changed, 102 insertions(+), 25 deletions(-)
 create mode 100644 drivers/acpi/osi.c

Comments

Rafael J. Wysocki Feb. 4, 2015, 1:50 p.m. UTC | #1
On Tuesday, February 03, 2015 05:21:40 PM al.stone@linaro.org wrote:
> From: Al Stone <al.stone@linaro.org>
> 
> In order to deprecate the use of _OSI for arm64 or other new architectures,
> we need to make the default handler something we can change for various
> platforms.  This patch moves the definition of acpi_osi_handler() -- the
> function used by ACPICA as a callback for evaluating _OSI -- into a separate
> file.  Subsequent patches will change which files get built so that we can
> then build the version of _OSI we need for a particular architecture.
> 
> There is no functional change.
> 
> Signed-off-by: Al Stone <al.stone@linaro.org>
> ---
>  drivers/acpi/Makefile |   2 +-
>  drivers/acpi/osi.c    | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/acpi/osl.c    |  24 ------------
>  include/linux/acpi.h  |   1 +
>  4 files changed, 102 insertions(+), 25 deletions(-)
>  create mode 100644 drivers/acpi/osi.c
> 
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index c346011..df348b3 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -18,7 +18,7 @@ obj-y				+= acpi.o \
>  					acpica/
>  
>  # All the builtin files are in the "acpi." module_param namespace.
> -acpi-y				+= osl.o utils.o reboot.o
> +acpi-y				+= osl.o utils.o reboot.o osi.o
>  acpi-y				+= nvs.o
>  
>  # Power management related files
> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
> new file mode 100644
> index 0000000..fff2b0c
> --- /dev/null
> +++ b/drivers/acpi/osi.c
> @@ -0,0 +1,100 @@
> +/*
> + *  osi.c - _OSI implementation (moved from drivers/acpi/osl.c)
> + *
> + *  Copyright (C) 2000       Andrew Henroid
> + *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
> + *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
> + *  Copyright (c) 2008 Intel Corporation
> + *   Author: Matthew Wilcox <willy@linux.intel.com>
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; either version 2 of the License, or
> + *  (at your option) any later version.
> + *
> + *  This program is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.

Nit: The street address of the FSF is not really useful here.  What if they move? :-)

> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, write to the Free Software
> + *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
> + */
> +
> +#include <linux/acpi.h>
> +
> +#define _COMPONENT		ACPI_OS_SERVICES
> +ACPI_MODULE_NAME("osl");
> +
> +#define PREFIX			"ACPI: "
> +
> +/*
> + * The story of _OSI(Linux)
> + *
> + * From pre-history through Linux-2.6.22,
> + * Linux responded TRUE upon a BIOS OSI(Linux) query.
> + *
> + * Unfortunately, reference BIOS writers got wind of this
> + * and put OSI(Linux) in their example code, quickly exposing
> + * this string as ill-conceived and opening the door to
> + * an un-bounded number of BIOS incompatibilities.
> + *
> + * For example, OSI(Linux) was used on resume to re-POST a
> + * video card on one system, because Linux at that time
> + * could not do a speedy restore in its native driver.
> + * But then upon gaining quick native restore capability,
> + * Linux has no way to tell the BIOS to skip the time-consuming
> + * POST -- putting Linux at a permanent performance disadvantage.
> + * On another system, the BIOS writer used OSI(Linux)
> + * to infer native OS support for IPMI!  On other systems,
> + * OSI(Linux) simply got in the way of Linux claiming to
> + * be compatible with other operating systems, exposing
> + * BIOS issues such as skipped device initialization.
> + *
> + * So "Linux" turned out to be a really poor chose of
> + * OSI string, and from Linux-2.6.23 onward we respond FALSE.
> + *
> + * BIOS writers should NOT query _OSI(Linux) on future systems.
> + * Linux will complain on the console when it sees it, and return FALSE.
> + * To get Linux to return TRUE for your system  will require
> + * a kernel source update to add a DMI entry,
> + * or boot with "acpi_osi=Linux"
> + */
> +
> +static struct osi_linux {
> +	unsigned int	enable:1;
> +	unsigned int	dmi:1;
> +	unsigned int	cmdline:1;
> +	unsigned int	default_disabling:1;
> +} osi_linux = {0, 0, 0, 0};
> +
> +u32 acpi_osi_handler(acpi_string interface, u32 supported)
> +{
> +	if (!strcmp("Linux", interface)) {
> +
> +		printk_once(KERN_NOTICE FW_BUG PREFIX
> +			"BIOS _OSI(Linux) query %s%s\n",
> +			osi_linux.enable ? "honored" : "ignored",
> +			osi_linux.cmdline ? " via cmdline" :
> +			osi_linux.dmi ? " via DMI" : "");
> +	}
> +
> +	if (!strcmp("Darwin", interface)) {
> +		/*
> +		 * Apple firmware will behave poorly if it receives positive
> +		 * answers to "Darwin" and any other OS. Respond positively
> +		 * to Darwin and then disable all other vendor strings.
> +		 */
> +		acpi_update_interfaces(ACPI_DISABLE_ALL_VENDOR_STRINGS);
> +		supported = ACPI_UINT32_MAX;
> +	}
> +
> +	return supported;
> +}
> +
> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> index f9eeae8..c7f1cd6 100644
> --- a/drivers/acpi/osl.c
> +++ b/drivers/acpi/osl.c
> @@ -141,30 +141,6 @@ static struct osi_linux {
>  	unsigned int	default_disabling:1;
>  } osi_linux = {0, 0, 0, 0};
>  
> -static u32 acpi_osi_handler(acpi_string interface, u32 supported)
> -{
> -	if (!strcmp("Linux", interface)) {
> -
> -		printk_once(KERN_NOTICE FW_BUG PREFIX
> -			"BIOS _OSI(Linux) query %s%s\n",
> -			osi_linux.enable ? "honored" : "ignored",
> -			osi_linux.cmdline ? " via cmdline" :
> -			osi_linux.dmi ? " via DMI" : "");
> -	}
> -
> -	if (!strcmp("Darwin", interface)) {
> -		/*
> -		 * Apple firmware will behave poorly if it receives positive
> -		 * answers to "Darwin" and any other OS. Respond positively
> -		 * to Darwin and then disable all other vendor strings.
> -		 */
> -		acpi_update_interfaces(ACPI_DISABLE_ALL_VENDOR_STRINGS);
> -		supported = ACPI_UINT32_MAX;
> -	}
> -
> -	return supported;
> -}
> -
>  static void __init acpi_request_region (struct acpi_generic_address *gas,
>  	unsigned int length, char *desc)
>  {
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 87f365e..ec18ab0 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -271,6 +271,7 @@ static inline int acpi_video_display_switch_support(void)
>  extern int acpi_blacklisted(void);
>  extern void acpi_dmi_osi_linux(int enable, const struct dmi_system_id *d);
>  extern void acpi_osi_setup(char *str);
> +extern u32 acpi_osi_handler(acpi_string interface, u32 supported);
>  
>  #ifdef CONFIG_ACPI_NUMA
>  int acpi_get_node(acpi_handle handle);
>
Al Stone Feb. 4, 2015, 10:44 p.m. UTC | #2
On 02/04/2015 06:50 AM, Rafael J. Wysocki wrote:
> On Tuesday, February 03, 2015 05:21:40 PM al.stone@linaro.org wrote:
>> From: Al Stone <al.stone@linaro.org>
>>
>> In order to deprecate the use of _OSI for arm64 or other new architectures,
>> we need to make the default handler something we can change for various
>> platforms.  This patch moves the definition of acpi_osi_handler() -- the
>> function used by ACPICA as a callback for evaluating _OSI -- into a separate
>> file.  Subsequent patches will change which files get built so that we can
>> then build the version of _OSI we need for a particular architecture.
>>
>> There is no functional change.
>>
>> Signed-off-by: Al Stone <al.stone@linaro.org>
>> ---
>>  drivers/acpi/Makefile |   2 +-
>>  drivers/acpi/osi.c    | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/acpi/osl.c    |  24 ------------
>>  include/linux/acpi.h  |   1 +
>>  4 files changed, 102 insertions(+), 25 deletions(-)
>>  create mode 100644 drivers/acpi/osi.c
>>
>> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
>> index c346011..df348b3 100644
>> --- a/drivers/acpi/Makefile
>> +++ b/drivers/acpi/Makefile
>> @@ -18,7 +18,7 @@ obj-y				+= acpi.o \
>>  					acpica/
>>  
>>  # All the builtin files are in the "acpi." module_param namespace.
>> -acpi-y				+= osl.o utils.o reboot.o
>> +acpi-y				+= osl.o utils.o reboot.o osi.o
>>  acpi-y				+= nvs.o
>>  
>>  # Power management related files
>> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
>> new file mode 100644
>> index 0000000..fff2b0c
>> --- /dev/null
>> +++ b/drivers/acpi/osi.c
>> @@ -0,0 +1,100 @@
>> +/*
>> + *  osi.c - _OSI implementation (moved from drivers/acpi/osl.c)
>> + *
>> + *  Copyright (C) 2000       Andrew Henroid
>> + *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
>> + *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
>> + *  Copyright (c) 2008 Intel Corporation
>> + *   Author: Matthew Wilcox <willy@linux.intel.com>
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; either version 2 of the License, or
>> + *  (at your option) any later version.
>> + *
>> + *  This program is distributed in the hope that it will be useful,
>> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + *  GNU General Public License for more details.
> 
> Nit: The street address of the FSF is not really useful here.  What if they move? :-)

This was one of the things checkpatch complained about, understandably :).  It's
a direct cut'n'paste from osl.c.

I can clean these up in the new file; would it help to clean up osl.c (at least
from checkpatch's point of view), as long as I'm at it?

>> + *
>> + *  You should have received a copy of the GNU General Public License
>> + *  along with this program; if not, write to the Free Software
>> + *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *
>> + */
[snip...]
Rafael J. Wysocki Feb. 4, 2015, 11:21 p.m. UTC | #3
On Wednesday, February 04, 2015 03:44:50 PM Al Stone wrote:
> On 02/04/2015 06:50 AM, Rafael J. Wysocki wrote:
> > On Tuesday, February 03, 2015 05:21:40 PM al.stone@linaro.org wrote:
> >> From: Al Stone <al.stone@linaro.org>
> >>
> >> In order to deprecate the use of _OSI for arm64 or other new architectures,
> >> we need to make the default handler something we can change for various
> >> platforms.  This patch moves the definition of acpi_osi_handler() -- the
> >> function used by ACPICA as a callback for evaluating _OSI -- into a separate
> >> file.  Subsequent patches will change which files get built so that we can
> >> then build the version of _OSI we need for a particular architecture.
> >>
> >> There is no functional change.
> >>
> >> Signed-off-by: Al Stone <al.stone@linaro.org>
> >> ---
> >>  drivers/acpi/Makefile |   2 +-
> >>  drivers/acpi/osi.c    | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >>  drivers/acpi/osl.c    |  24 ------------
> >>  include/linux/acpi.h  |   1 +
> >>  4 files changed, 102 insertions(+), 25 deletions(-)
> >>  create mode 100644 drivers/acpi/osi.c
> >>
> >> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> >> index c346011..df348b3 100644
> >> --- a/drivers/acpi/Makefile
> >> +++ b/drivers/acpi/Makefile
> >> @@ -18,7 +18,7 @@ obj-y				+= acpi.o \
> >>  					acpica/
> >>  
> >>  # All the builtin files are in the "acpi." module_param namespace.
> >> -acpi-y				+= osl.o utils.o reboot.o
> >> +acpi-y				+= osl.o utils.o reboot.o osi.o
> >>  acpi-y				+= nvs.o
> >>  
> >>  # Power management related files
> >> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
> >> new file mode 100644
> >> index 0000000..fff2b0c
> >> --- /dev/null
> >> +++ b/drivers/acpi/osi.c
> >> @@ -0,0 +1,100 @@
> >> +/*
> >> + *  osi.c - _OSI implementation (moved from drivers/acpi/osl.c)
> >> + *
> >> + *  Copyright (C) 2000       Andrew Henroid
> >> + *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
> >> + *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
> >> + *  Copyright (c) 2008 Intel Corporation
> >> + *   Author: Matthew Wilcox <willy@linux.intel.com>
> >> + *
> >> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> + *
> >> + *  This program is free software; you can redistribute it and/or modify
> >> + *  it under the terms of the GNU General Public License as published by
> >> + *  the Free Software Foundation; either version 2 of the License, or
> >> + *  (at your option) any later version.
> >> + *
> >> + *  This program is distributed in the hope that it will be useful,
> >> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> >> + *  GNU General Public License for more details.
> > 
> > Nit: The street address of the FSF is not really useful here.  What if they move? :-)
> 
> This was one of the things checkpatch complained about, understandably :).  It's
> a direct cut'n'paste from osl.c.
> 
> I can clean these up in the new file; would it help to clean up osl.c (at least
> from checkpatch's point of view), as long as I'm at it?

Yeah, won't hurt. :-)

In a separate patch please, though.
al.stone@linaro.org Feb. 4, 2015, 11:49 p.m. UTC | #4
On 02/04/2015 04:21 PM, Rafael J. Wysocki wrote:
> On Wednesday, February 04, 2015 03:44:50 PM Al Stone wrote:
>> On 02/04/2015 06:50 AM, Rafael J. Wysocki wrote:
>>> On Tuesday, February 03, 2015 05:21:40 PM al.stone@linaro.org wrote:
>>>> From: Al Stone <al.stone@linaro.org>
>>>>
>>>> In order to deprecate the use of _OSI for arm64 or other new architectures,
>>>> we need to make the default handler something we can change for various
>>>> platforms.  This patch moves the definition of acpi_osi_handler() -- the
>>>> function used by ACPICA as a callback for evaluating _OSI -- into a separate
>>>> file.  Subsequent patches will change which files get built so that we can
>>>> then build the version of _OSI we need for a particular architecture.
>>>>
>>>> There is no functional change.
>>>>
>>>> Signed-off-by: Al Stone <al.stone@linaro.org>
>>>> ---
>>>>  drivers/acpi/Makefile |   2 +-
>>>>  drivers/acpi/osi.c    | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>>>  drivers/acpi/osl.c    |  24 ------------
>>>>  include/linux/acpi.h  |   1 +
>>>>  4 files changed, 102 insertions(+), 25 deletions(-)
>>>>  create mode 100644 drivers/acpi/osi.c
>>>>
>>>> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
>>>> index c346011..df348b3 100644
>>>> --- a/drivers/acpi/Makefile
>>>> +++ b/drivers/acpi/Makefile
>>>> @@ -18,7 +18,7 @@ obj-y				+= acpi.o \
>>>>  					acpica/
>>>>  
>>>>  # All the builtin files are in the "acpi." module_param namespace.
>>>> -acpi-y				+= osl.o utils.o reboot.o
>>>> +acpi-y				+= osl.o utils.o reboot.o osi.o
>>>>  acpi-y				+= nvs.o
>>>>  
>>>>  # Power management related files
>>>> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
>>>> new file mode 100644
>>>> index 0000000..fff2b0c
>>>> --- /dev/null
>>>> +++ b/drivers/acpi/osi.c
>>>> @@ -0,0 +1,100 @@
>>>> +/*
>>>> + *  osi.c - _OSI implementation (moved from drivers/acpi/osl.c)
>>>> + *
>>>> + *  Copyright (C) 2000       Andrew Henroid
>>>> + *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
>>>> + *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
>>>> + *  Copyright (c) 2008 Intel Corporation
>>>> + *   Author: Matthew Wilcox <willy@linux.intel.com>
>>>> + *
>>>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>> + *
>>>> + *  This program is free software; you can redistribute it and/or modify
>>>> + *  it under the terms of the GNU General Public License as published by
>>>> + *  the Free Software Foundation; either version 2 of the License, or
>>>> + *  (at your option) any later version.
>>>> + *
>>>> + *  This program is distributed in the hope that it will be useful,
>>>> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
>>>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>>>> + *  GNU General Public License for more details.
>>>
>>> Nit: The street address of the FSF is not really useful here.  What if they move? :-)
>>
>> This was one of the things checkpatch complained about, understandably :).  It's
>> a direct cut'n'paste from osl.c.
>>
>> I can clean these up in the new file; would it help to clean up osl.c (at least
>> from checkpatch's point of view), as long as I'm at it?
> 
> Yeah, won't hurt. :-)
> 
> In a separate patch please, though.
> 
> 

Of course.  Will do.
diff mbox

Patch

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index c346011..df348b3 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -18,7 +18,7 @@  obj-y				+= acpi.o \
 					acpica/
 
 # All the builtin files are in the "acpi." module_param namespace.
-acpi-y				+= osl.o utils.o reboot.o
+acpi-y				+= osl.o utils.o reboot.o osi.o
 acpi-y				+= nvs.o
 
 # Power management related files
diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
new file mode 100644
index 0000000..fff2b0c
--- /dev/null
+++ b/drivers/acpi/osi.c
@@ -0,0 +1,100 @@ 
+/*
+ *  osi.c - _OSI implementation (moved from drivers/acpi/osl.c)
+ *
+ *  Copyright (C) 2000       Andrew Henroid
+ *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
+ *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ *  Copyright (c) 2008 Intel Corporation
+ *   Author: Matthew Wilcox <willy@linux.intel.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ */
+
+#include <linux/acpi.h>
+
+#define _COMPONENT		ACPI_OS_SERVICES
+ACPI_MODULE_NAME("osl");
+
+#define PREFIX			"ACPI: "
+
+/*
+ * The story of _OSI(Linux)
+ *
+ * From pre-history through Linux-2.6.22,
+ * Linux responded TRUE upon a BIOS OSI(Linux) query.
+ *
+ * Unfortunately, reference BIOS writers got wind of this
+ * and put OSI(Linux) in their example code, quickly exposing
+ * this string as ill-conceived and opening the door to
+ * an un-bounded number of BIOS incompatibilities.
+ *
+ * For example, OSI(Linux) was used on resume to re-POST a
+ * video card on one system, because Linux at that time
+ * could not do a speedy restore in its native driver.
+ * But then upon gaining quick native restore capability,
+ * Linux has no way to tell the BIOS to skip the time-consuming
+ * POST -- putting Linux at a permanent performance disadvantage.
+ * On another system, the BIOS writer used OSI(Linux)
+ * to infer native OS support for IPMI!  On other systems,
+ * OSI(Linux) simply got in the way of Linux claiming to
+ * be compatible with other operating systems, exposing
+ * BIOS issues such as skipped device initialization.
+ *
+ * So "Linux" turned out to be a really poor chose of
+ * OSI string, and from Linux-2.6.23 onward we respond FALSE.
+ *
+ * BIOS writers should NOT query _OSI(Linux) on future systems.
+ * Linux will complain on the console when it sees it, and return FALSE.
+ * To get Linux to return TRUE for your system  will require
+ * a kernel source update to add a DMI entry,
+ * or boot with "acpi_osi=Linux"
+ */
+
+static struct osi_linux {
+	unsigned int	enable:1;
+	unsigned int	dmi:1;
+	unsigned int	cmdline:1;
+	unsigned int	default_disabling:1;
+} osi_linux = {0, 0, 0, 0};
+
+u32 acpi_osi_handler(acpi_string interface, u32 supported)
+{
+	if (!strcmp("Linux", interface)) {
+
+		printk_once(KERN_NOTICE FW_BUG PREFIX
+			"BIOS _OSI(Linux) query %s%s\n",
+			osi_linux.enable ? "honored" : "ignored",
+			osi_linux.cmdline ? " via cmdline" :
+			osi_linux.dmi ? " via DMI" : "");
+	}
+
+	if (!strcmp("Darwin", interface)) {
+		/*
+		 * Apple firmware will behave poorly if it receives positive
+		 * answers to "Darwin" and any other OS. Respond positively
+		 * to Darwin and then disable all other vendor strings.
+		 */
+		acpi_update_interfaces(ACPI_DISABLE_ALL_VENDOR_STRINGS);
+		supported = ACPI_UINT32_MAX;
+	}
+
+	return supported;
+}
+
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index f9eeae8..c7f1cd6 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -141,30 +141,6 @@  static struct osi_linux {
 	unsigned int	default_disabling:1;
 } osi_linux = {0, 0, 0, 0};
 
-static u32 acpi_osi_handler(acpi_string interface, u32 supported)
-{
-	if (!strcmp("Linux", interface)) {
-
-		printk_once(KERN_NOTICE FW_BUG PREFIX
-			"BIOS _OSI(Linux) query %s%s\n",
-			osi_linux.enable ? "honored" : "ignored",
-			osi_linux.cmdline ? " via cmdline" :
-			osi_linux.dmi ? " via DMI" : "");
-	}
-
-	if (!strcmp("Darwin", interface)) {
-		/*
-		 * Apple firmware will behave poorly if it receives positive
-		 * answers to "Darwin" and any other OS. Respond positively
-		 * to Darwin and then disable all other vendor strings.
-		 */
-		acpi_update_interfaces(ACPI_DISABLE_ALL_VENDOR_STRINGS);
-		supported = ACPI_UINT32_MAX;
-	}
-
-	return supported;
-}
-
 static void __init acpi_request_region (struct acpi_generic_address *gas,
 	unsigned int length, char *desc)
 {
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 87f365e..ec18ab0 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -271,6 +271,7 @@  static inline int acpi_video_display_switch_support(void)
 extern int acpi_blacklisted(void);
 extern void acpi_dmi_osi_linux(int enable, const struct dmi_system_id *d);
 extern void acpi_osi_setup(char *str);
+extern u32 acpi_osi_handler(acpi_string interface, u32 supported);
 
 #ifdef CONFIG_ACPI_NUMA
 int acpi_get_node(acpi_handle handle);