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Diffstat (limited to 'Documentation/admin-guide/bootconfig.rst')
| -rw-r--r-- | Documentation/admin-guide/bootconfig.rst | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst index 91339efdcb54..f712758472d5 100644 --- a/Documentation/admin-guide/bootconfig.rst +++ b/Documentation/admin-guide/bootconfig.rst @@ -20,18 +20,26 @@ Config File Syntax The boot config syntax is a simple structured key-value. Each key consists of dot-connected-words, and key and value are connected by ``=``. The value -has to be terminated by semi-colon (``;``) or newline (``\n``). -For array value, array entries are separated by comma (``,``). :: - - KEY[.WORD[...]] = VALUE[, VALUE2[...]][;] - -Unlike the kernel command line syntax, spaces are OK around the comma and ``=``. +string has to be terminated by the following delimiters described below. Each key word must contain only alphabets, numbers, dash (``-``) or underscore (``_``). And each value only contains printable characters or spaces except for delimiters such as semi-colon (``;``), new-line (``\n``), comma (``,``), hash (``#``) and closing brace (``}``). +If the ``=`` is followed by whitespace up to one of these delimiters, the +key is assigned an empty value. + +For arrays, the array values are comma (``,``) separated, and comments and +line breaks with newline (``\n``) are allowed between array values for +readability. Thus the first entry of the array must be on the same line as +the key.:: + + KEY[.WORD[...]] = VALUE[, VALUE2[...]][;] + +Unlike the kernel command line syntax, white spaces (including tabs) are +ignored around the comma and ``=``. + If you want to use those delimiters in a value, you can use either double- quotes (``"VALUE"``) or single-quotes (``'VALUE'``) to quote it. Note that you can not escape these quotes. @@ -138,8 +146,8 @@ This is parsed as below:: foo = value bar = 1, 2, 3 -Note that you can not put a comment between value and delimiter(``,`` or -``;``). This means following config has a syntax error :: +Note that you can NOT put a comment or a newline between value and delimiter +(``,`` or ``;``). This means following config has a syntax error :: key = 1 # comment ,2 @@ -265,7 +273,7 @@ The final kernel cmdline will be the following:: Config File Limitation ====================== -Currently the maximum config size size is 32KB and the total key-words (not +Currently the maximum config size is 32KB and the total key-words (not key-value entries) must be under 1024 nodes. Note: this is not the number of entries but nodes, an entry must consume more than 2 nodes (a key-word and a value). So theoretically, it will be |