Re: [PATCH] Revised patch

Randy Dunlap
2011-06-09T17:47:25Z

On Thu, 9 Jun 2011 18:33:46 +0100 Andrew Murray wrote:

> Hi,
>
> I've updated this patch based on your feedback. This covers all the recent feedback.
>
> From: Andrew Murray <amurray@mpc-data.co.uk>
>
> This patch updates the incomplete documentation concerning the printk
> extended format specifiers.

Thanks. A few comments below...

> Signed-off-by: Andrew Murray <amurray@mpc-data.co.uk>
>
> ---
> Documentation/printk-formats.txt | 113 +++++++++++++++++++++++++++++++++++++-
> 1 files changed, 111 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
> index 1b5a5dd..2968cbf 100644
> --- a/Documentation/printk-formats.txt
> +++ b/Documentation/printk-formats.txt
> @@ -9,7 +9,115 @@ 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
> +
> + 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.
> +
> + 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.
> +

I would hyphenate the -endian types, but won't insist on that.

> +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'

16-bit

> + 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',

16-byte

> + '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):

%pB is missing?
* - 'B' For backtraced symbolic direct pointers with offset

> @@ -32,4 +140,5 @@ 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>
> --

---
~Randy
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