From d7ec9a05d6defda8432da574a2a888eed6fc29f6 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 6 Nov 2015 16:30:35 -0800 Subject: lib/vsprintf.c: update documentation %n is no longer just ignored; it results in early return from vsnprintf. Also add a request to add test cases for future %p extensions. Signed-off-by: Rasmus Villemoes Reviewed-by: Martin Kletzander Reviewed-by: Andy Shevchenko Cc: Jonathan Corbet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/printk-formats.txt | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'Documentation/printk-formats.txt') diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt index 9b8d7f746b1a..b784c270105f 100644 --- a/Documentation/printk-formats.txt +++ b/Documentation/printk-formats.txt @@ -23,6 +23,10 @@ Example: Reminder: sizeof() result is of type size_t. +The kernel's printf does not support %n. For obvious reasons, floating +point formats (%e, %f, %g, %a) are also not recognized. Use of any +unsupported specifier or length qualifier results in a WARN and early +return from vsnprintf. Raw pointer value SHOULD be printed with %p. The kernel supports the following extended format specifiers for pointer types: @@ -305,13 +309,9 @@ Command from struct task_struct Passed by reference. -Ignored argument: +If you add other %p extensions, please extend lib/test_printf.c with +one or more test cases, if at all feasible. - %n %n - - The argument passed will be ignored. In other words, literal "%n" will - be in the output and the argument will be considered for next format - specifier. Thank you for your cooperation and attention. -- cgit v1.2.3