Re: [PATCH] printk-formats.txt documentation update

Andrew Murray
2011-06-10T17:56:38Z

Great! Thanks for the help.

On 10 June 2011 18:50, Randy Dunlap <rdunlap@xenotime.net> wrote:
> On Thu,  9 Jun 2011 22:24:48 +0100 Andrew Murray wrote:
>
>> From: Andrew Murray <amurray@mpc-data.co.uk>
>>
>> This patch updates the incomplete documentation concerning the printk
>> extended format specifiers
>>
>> Signed-off-by: Andrew Murray <amurray@mpc-data.co.uk>
>
> Applied with minor tweaks (including dropping trailing whitespace).
>
> Thanks.
>
>> ---
>>  Documentation/printk-formats.txt |  119 +++++++++++++++++++++++++++++++++++++-
>>  1 files changed, 117 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
>> index 1b5a5dd..6455e5b 100644
>> --- a/Documentation/printk-formats.txt
>> +++ b/Documentation/printk-formats.txt
>> @@ -9,7 +9,121 @@ If variable is of Type,             use printk format specifier:
>>               size_t                  %zu or %zx
>>               ssize_t                 %zd or %zx
>>
>> -Raw pointer value SHOULD be printed with %p.
>> +Raw pointer value SHOULD be printed with %p. The kernel supports
>> +the following extended format specifiers for pointer types:
>> +
>> +Symbols/Function Pointers:
>> +
>> +     %pF     versatile_init+0x0/0x110
>> +     %pf     versatile_init
>> +     %pS     versatile_init+0x0/0x110
>> +     %ps     versatile_init
>> +     %pB     prev_fn_of_versatile_init+0x88/0x88
>> +
>> +     For printing symbols and function pointers. The 'S' and 's' specifiers
>> +     result in the symbol name with ('S') or without ('s') offsets. Where
>> +     this is used on a kernel without KALLSYMS - the symbol address is
>> +     printed instead.
>> +
>> +     The 'B' specifier results in the symbol name with offsets and should be
>> +     used when printing stack backtraces. The specifier takes into
>> +     consideration the effect of compiler optimisations which may occur
>> +     when tail-call's are used and marked with the noreturn GCC attribute.
>> +
>> +     On ia64, ppc64 and parisc64 architectures function pointers are
>> +     actually function descriptors which must first be resolved. The 'F' and
>> +     'f' specifiers perform this resolution and then provide the same
>> +     functionality as the 'S' and 's' specifiers.
>> +
>> +Kernel Pointers:
>> +
>> +     %pK     0x01234567 or 0x0123456789abcdef
>> +
>> +     For printing kernel pointers which should be hidden from unprivileged
>> +     users. The behaviour of %pK depends on the kptr_restrict sysctl - see
>> +     Documentation/sysctl/kernel.txt for more details.
>> +
>> +Struct Resources:
>> +
>> +     %pr     [mem 0x60000000-0x6fffffff flags 0x2200] or
>> +             [mem 0x0000000060000000-0x000000006fffffff flags 0x2200]
>> +     %pR     [mem 0x60000000-0x6fffffff pref] or
>> +             [mem 0x0000000060000000-0x000000006fffffff pref]
>> +
>> +     For printing struct resources. The 'R' and 'r' specifiers result in a
>> +     printed resource with ('R') or without ('r') a decoded flags member.
>> +
>> +MAC/FDDI addresses:
>> +
>> +     %pM     00:01:02:03:04:05
>> +     %pMF    00-01-02-03-04-05
>> +     %pm     000102030405
>> +
>> +     For printing 6-byte MAC/FDDI addresses in hex notation. The 'M' and 'm'
>> +     specifiers result in a printed address with ('M') or without ('m') byte
>> +     separators. The default byte separator is the colon (':').
>> +
>> +     Where FDDI addresses are concerned the 'F' specifier can be used after
>> +     the 'M' specifier to use dash ('-') separators instead of the default
>> +     separator.
>> +
>> +IPv4 addresses:
>> +
>> +     %pI4    1.2.3.4
>> +     %pi4    001.002.003.004
>> +     %p[Ii][hnbl]
>> +
>> +     For printing IPv4 dot-separated decimal addresses. The 'I4' and 'i4'
>> +     specifiers result in a printed address with ('i4') or without ('I4')
>> +     leading zeros.
>> +
>> +     The additional 'h', 'n', 'b', and 'l' specifiers are used to specify
>> +     host, network, big or little endian order addresses respectively. Where
>> +     no specifier is provided the default network/big endian order is used.
>> +
>> +IPv6 addresses:
>> +
>> +     %pI6    0001:0002:0003:0004:0005:0006:0007:0008
>> +     %pi6    00010002000300040005000600070008
>> +     %pI6c   1:2:3:4:5:6:7:8
>> +
>> +     For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6'
>> +     specifiers result in a printed address with ('I6') or without ('i6')
>> +     colon-separators. Leading zeros are always used.
>> +
>> +     The additional 'c' specifier can be used with the 'I' specifier to
>> +     print a compressed IPv6 address as described by
>> +     http://tools.ietf.org/html/rfc5952
>> +
>> +UUID/GUID addresses:
>> +
>> +     %pUb    00010203-0405-0607-0809-0a0b0c0d0e0f
>> +     %pUB    00010203-0405-0607-0809-0A0B0C0D0E0F
>> +     %pUl    03020100-0504-0706-0809-0a0b0c0e0e0f
>> +     %pUL    03020100-0504-0706-0809-0A0B0C0E0E0F
>> +
>> +     For printing-16 byte UUID/GUIDs addresses. The additional 'l', 'L',
>> +     'b' and 'B' specifiers are used to specify a little endian order in
>> +     lower ('l') or upper case ('L') hex characters - and big endian order
>> +     in lower ('b') or upper case ('B') hex characters.
>> +
>> +     Where no additional specifiers are used the default little endian
>> +     order with lower case hex characters will be printed.
>> +
>> +struct va_format:
>> +
>> +     %pV
>> +
>> +     For printing struct va_format structures. These contain a format string
>> +     and va_list as follows:
>> +
>> +     struct va_format {
>> +             const char *fmt;
>> +             va_list *va;
>> +     };
>> +
>> +     Do not use this feature without some mechanism to verify the
>> +     correctness of the format string and va_list arguments.
>>
>>  u64 SHOULD be printed with %llu/%llx, (unsigned long long):
>>
>> @@ -32,4 +146,5 @@ Reminder: sizeof() result is of type size_t.
>>  Thank you for your cooperation and attention.
>>
>>
>> -By Randy Dunlap <rdunlap@xenotime.net>
>> +By Randy Dunlap <rdunlap@xenotime.net> and
>> +Andrew Murray <amurray@mpc-data.co.uk>
>> --
>> 1.7.4.1
>>
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>
> ---
> ~Randy
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
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