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-rw-r--r--Documentation/printk-formats.txt32
1 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index b4498218c474..5a615c14f75d 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -70,6 +70,38 @@ DMA addresses types dma_addr_t:
For printing a dma_addr_t type which can vary based on build options,
regardless of the width of the CPU data path. Passed by reference.
+Raw buffer as an escaped string:
+
+ %*pE[achnops]
+
+ For printing raw buffer as an escaped string. For the following buffer
+
+ 1b 62 20 5c 43 07 22 90 0d 5d
+
+ few examples show how the conversion would be done (the result string
+ without surrounding quotes):
+
+ %*pE "\eb \C\a"\220\r]"
+ %*pEhp "\x1bb \C\x07"\x90\x0d]"
+ %*pEa "\e\142\040\\\103\a\042\220\r\135"
+
+ The conversion rules are applied according to an optional combination
+ of flags (see string_escape_mem() kernel documentation for the
+ details):
+ a - ESCAPE_ANY
+ c - ESCAPE_SPECIAL
+ h - ESCAPE_HEX
+ n - ESCAPE_NULL
+ o - ESCAPE_OCTAL
+ p - ESCAPE_NP
+ s - ESCAPE_SPACE
+ By default ESCAPE_ANY_NP is used.
+
+ ESCAPE_ANY_NP is the sane choice for many cases, in particularly for
+ printing SSIDs.
+
+ If field width is omitted the 1 byte only will be escaped.
+
Raw buffer as a hex string:
%*ph 00 01 02 ... 3f
%*phC 00:01:02: ... :3f