linux-kernel - Re: How to export information larger than PROC_BLOCK

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Message-ID: <BANLkTinDUec911Fg4Nw_qO=uARJVv9GZBQ@mail.gmail.com>
Date:	Wed, 27 Apr 2011 00:16:35 -0400
From:	Jidong Xiao <jidong.xiao@...il.com>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	"Am??rico Wang" <xiyou.wangcong@...il.com>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: How to export information larger than PROC_BLOCK_SIZE via /proc
 file system?

On Tue, Apr 26, 2011 at 11:18 PM, Alexey Dobriyan <adobriyan@...il.com> wrote:
> On Wed, Apr 27, 2011 at 11:00:32AM +0800, Am??rico Wang wrote:
>> On Wed, Apr 27, 2011 at 8:54 AM, Jidong Xiao <jidong.xiao@...il.com> wrote:
>> > Hi,
>> >
>> > I am tracing some data inside the kernel, and I plan to export the
>> > tracing data through /proc file system. I created a file under /proc
>> > file system, and I use cat to display the tracing data. However, every
>> > time there is only 3072 bytes data displayed, which is the size
>> > defined by PROC_BLOCK_SIZE. And I wonder that how to export
>> > information more than that limit? Judging from the function
>> > fs/proc/generic.c/proc_file_read(), if the size returned by my
>> > read_proc function is large than a PAGE_SIZE, then I will get a
>> > KERN_ERR message which says "proc_file_read: Apparent buffer
>> > overflow!". Any help would be appreciated!
>> >
>>
>> Why not switch to use debugfs?
>
> Or use seq_file/proc_create.
>

Oh, thank you two very much. After reading the related document, I
feel seq_file is exactly what I am looking for.

Regards
Jidong
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