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authorLv Zheng <lv.zheng@intel.com>2013-07-22 12:08:25 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-07-23 06:06:56 +0400
commit5dc17986fdc3d2425838cb8d699152c3c30d1208 (patch)
tree7937dfdaacca0a6613daed8e50468d4fe2df697a /drivers/acpi/osl.c
parent2cf9f5bcc8d8cb31d6ea7baebac5056f39fb4f40 (diff)
downloadlinux-5dc17986fdc3d2425838cb8d699152c3c30d1208.tar.xz
ACPI: Add facility to disable all _OSI OS vendor strings
This patch introduces "acpi_osi=!" command line to force Linux replying "UNSUPPORTED" to all of the _OSI strings. This patch is based on an ACPICA enhancement - the new API acpi_update_interfaces(). The _OSI object provides the platform with the ability to query OSPM to determine the set of ACPI related interfaces, behaviors, or features that the operating system supports. The argument passed to the _OSI is a string like the followings: 1. Feature Group String, examples include Module Device Processor Device 3.0 _SCP Extensions Processor Aggregator Device ... 2. OS Vendor String, examples include Linux FreeBSD Windows ... There are AML codes provided in the ACPI namespace written in the following style to determine OSPM interfaces / features: Method(OSCK) { if (CondRefOf(_OSI, Local0)) { if (\_OSI("Windows")) { Return (One) } if (\_OSI("Windows 2006")) { Return (Ones) } Return (Zero) } Return (Zero) } There is a debugging facility implemented in Linux. Users can pass "acpi_osi=" boot parameters to the kernel to tune the _OSI evaluation result so that certain AML codes can be executed. Current implementation includes: 1. 'acpi_osi=' - this makes CondRefOf(_OSI, Local0) TRUE 2. 'acpi_osi="Windows"' - this makes \_OSI("Windows") TRUE 3. 'acpi_osi="!Windows"' - this makes \_OSI("Windows") FALSE The function to implement this feature is also used as a quirk mechanism in the Linux ACPI subystem. When _OSI is evaluatated by the AML codes, ACPICA replies "SUPPORTED" to all Windows operating system vendor strings. This is because Windows operating systems return "SUPPORTED" if the argument to the _OSI method specifies an earlier version of Windows. Please refer to the following MSDN document: How to Identify the Windows Version in ACPI by Using _OSI http://msdn.microsoft.com/en-us/library/hardware/gg463275.aspx This adds difficulties when developers want to feed specific Windows operating system vendor string to the BIOS codes for debugging purpose, multiple acpi_osi="!xxx" have to be specified in the command line to force Linux replying "UNSUPPORTED" to the Windows OS vendor strings listed in the AML codes. Signed-off-by: Lv Zheng <lv.zheng@intel.com> Reviewed-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Len Brown <len.brown@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/osl.c')
-rw-r--r--drivers/acpi/osl.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 6ab2c3505520..e8baa408faef 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -140,7 +140,8 @@ static struct osi_linux {
unsigned int enable:1;
unsigned int dmi:1;
unsigned int cmdline:1;
-} osi_linux = {0, 0, 0};
+ unsigned int default_disabling:1;
+} osi_linux = {0, 0, 0, 0};
static u32 acpi_osi_handler(acpi_string interface, u32 supported)
{
@@ -1376,6 +1377,10 @@ void __init acpi_osi_setup(char *str)
if (*str == '!') {
str++;
+ if (*str == '\0') {
+ osi_linux.default_disabling = 1;
+ return;
+ }
enable = false;
}
@@ -1441,6 +1446,13 @@ static void __init acpi_osi_setup_late(void)
int i;
acpi_status status;
+ if (osi_linux.default_disabling) {
+ status = acpi_update_interfaces(ACPI_DISABLE_ALL_VENDOR_STRINGS);
+
+ if (ACPI_SUCCESS(status))
+ printk(KERN_INFO PREFIX "Disabled all _OSI OS vendors\n");
+ }
+
for (i = 0; i < OSI_STRING_ENTRIES_MAX; i++) {
osi = &osi_setup_entries[i];
str = osi->string;