2 files changed, 40 insertions, 3 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 15356aca938c..d0d9cf278ae3 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -235,10 +235,35 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         Format: To spoof as Windows 98: ="Microsoft Windows"
 
         acpi_osi=       [HW,ACPI] Modify list of supported OS interface strings
-                        acpi_osi="string1"      # add string1 -- only one string
-                        acpi_osi="!string2"     # remove built-in string2
+                        acpi_osi="string1"      # add string1
+                        acpi_osi="!string2"     # remove string2
+                        acpi_osi=!              # disable all built-in OS vendor
+                                                  strings
                         acpi_osi=               # disable all strings
 
+                        'acpi_osi=!' can be used in combination with single or
+                        multiple 'acpi_osi="string1"' to support specific OS
+                        vendor string(s).  Note that such command can only
+                        affect the default state of the OS vendor strings, thus
+                        it cannot affect the default state of the feature group
+                        strings and the current state of the OS vendor strings,
+                        specifying it multiple times through kernel command line
+                        is meaningless.
+                        Examples:
+                          1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
+                             to 'acpi_osi="Windows 2000" acpi_osi=!', they all
+                             can make '_OSI("Windows 2000")' TRUE.
+
+                        'acpi_osi=' cannot be used in combination with other
+                        'acpi_osi=' command lines, the _OSI method will not
+                        exist in the ACPI namespace.  NOTE that such command can
+                        only affect the _OSI support state, thus specifying it
+                        multiple times through kernel command line is also
+                        meaningless.
+                        Examples:
+                          1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
+                             FALSE.
+
         acpi_pm_good    [X86]
                         Override the pmtimer bug detection: force the kernel
                         to assume that this machine's pmtimer latches its value
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;