linux-kernel - Re: [PATCH] lib: vsprintf: Add %pa format specifier for phys_addr

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Date:	Tue, 22 Jan 2013 09:29:27 +0200
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Stepan Moskovchenko <stepanm@...eaurora.org>
Cc:	Rob Landley <rob@...dley.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	George Spelvin <linux@...izon.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Andrei Emeltchenko <andrei.emeltchenko@...el.com>,
	mingo@...nel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] lib: vsprintf: Add %pa format specifier for phys_addr_t
 types

On Mon, 2013-01-21 at 21:47 -0800, Stepan Moskovchenko wrote: 
> Add the %pa format specifier for printing a phys_addr_t
> type, since the physical address size on some platforms
> can vary based on build options, regardless of the native
> integer type.
> 
> Signed-off-by: Stepan Moskovchenko <stepanm@...eaurora.org>
> ---
>  Documentation/printk-formats.txt |   13 ++++++++++---
>  lib/vsprintf.c                   |    7 +++++++
>  2 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
> index 8ffb274..dbc977b 100644
> --- a/Documentation/printk-formats.txt
> +++ b/Documentation/printk-formats.txt
> @@ -53,6 +53,13 @@ Struct Resources:
>  	For printing struct resources. The 'R' and 'r' specifiers result in a
>  	printed resource with ('R') or without ('r') a decoded flags member.
> 
> +Physical addresses:
> +
> +	%pa	0x01234567 or 0x0123456789abcdef
> +
> +	For printing a phys_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 a hex string:
>  	%*ph	00 01 02  ...  3f
>  	%*phC	00:01:02: ... :3f
> @@ -150,9 +157,9 @@ s64 SHOULD be printed with %lld/%llx, (long long):
>  	printk("%lld", (long long)s64_var);
> 
>  If <type> is dependent on a config option for its size (e.g., sector_t,
> -blkcnt_t, phys_addr_t, resource_size_t) or is architecture-dependent
> -for its size (e.g., tcflag_t), use a format specifier of its largest
> -possible type and explicitly cast to it.  Example:
> +blkcnt_t, resource_size_t) or is architecture-dependent for its size (e.g.,

resource_size_t is a typedef of phys_addr_t.

Probably you should mention that your change related to the phys_addr_t
*and* derivatives.

> +tcflag_t), use a format specifier of its largest possible type and explicitly
> +cast to it.  Example:
> 
>  	printk("test: sector number/total blocks: %llu/%llu\n",
>  		(unsigned long long)sector, (unsigned long long)blockcount);
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 39c99fe..9b02a71 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1022,6 +1022,7 @@ int kptr_restrict __read_mostly;
>   *              N no separator
>   *            The maximum supported length is 64 bytes of the input. Consider
>   *            to use print_hex_dump() for the larger input.
> + * - 'a' For a phys_addr_t type (passed by reference)
>   *
>   * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
>   * function pointers are really function descriptors, which contain a
> @@ -1112,6 +1113,12 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
>  			return netdev_feature_string(buf, end, ptr, spec);
>  		}
>  		break;
> +	case 'a':
> +		spec.flags |= SPECIAL | SMALL | ZEROPAD;
> +		spec.field_width = sizeof(phys_addr_t) * 2;
> +		spec.base = 16;
> +		return number(buf, end,
> +			      (unsigned long long) *((phys_addr_t *)ptr), spec);
>  	}
>  	spec.flags |= SMALL;
>  	if (spec.field_width == -1) {
> --
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
> 

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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