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-rw-r--r--Documentation/kernel-parameters.txt29
1 files changed, 27 insertions, 2 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