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From: "Randy.Dunlap" <>
To: selvakumar nagendran <>
Subject: Re: Module : Pipefs : doubts
Date: Mon, 10 Jan 2005 06:48:10 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

selvakumar nagendran wrote:
> Hello Randy,
>      Thanks for ur help. See I do know that pipe.o is
> compiled into the main kernel image. But the following
> code block in pipe.c, made me to think as if pipefs
> has been implemented as a module in the kernel. Bcoz
> it used module_init and module_exit macros. That's why
> I got confused. Can u explain the reason for this?

Here's what I suggest.  Look at the kernel header files,
in particular: include/linux/init.h .

Find /module_init/ in that header file.
It has different #defines depending on whether the
including file (e.g., pipe.c) is being
built as a module or not (#ifdef MODULE).

Once you have found that module_init() means __initcall(),
then you can find that __initcall() means device_initcall(),
which in turns means define_initcall("6",fn);
which is a (normal, common) method of setting up a
"module" (functional module, not only for separate
loadable modules) initialization entry point.
There, darn, I've said too much and my rubout key
doesn't work.

> ------------------
> static DECLARE_FSTYPE(pipe_fs_type, "pipefs",
> pipefs_read_super, FS_NOMOUNT);
> static int __init init_pipe_fs(void)
> {
> 	int err = register_filesystem(&pipe_fs_type);
> 	if (!err) {
> 		pipe_mnt = kern_mount(&pipe_fs_type);
> 		err = PTR_ERR(pipe_mnt);
> 		if (IS_ERR(pipe_mnt))
> 			unregister_filesystem(&pipe_fs_type);
> 		else
> 			err = 0;
> 	}
> 	return err;
> }
> static void __exit exit_pipe_fs(void)
> {
> 	unregister_filesystem(&pipe_fs_type);
> 	mntput(pipe_mnt);
> }
> module_init(init_pipe_fs)
> module_exit(exit_pipe_fs)
> --- "Randy.Dunlap" <> wrote:
>>selvakumar nagendran wrote:
>>>Hello linux-experts,
>>>    I went through the kernel source code file
>>>/fs/pipe.c and I found that the pipe file system
>>>configured as a module. But in lsmod I am unable
>>>see it. This is my first doubt.
>  Where do you see that?
>  fs/pipe.o is always built into the kernel image.


      reply	other threads:[~2005-01-10 15:40 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-01-10  5:04 Pipefs : doubts selvakumar nagendran
2005-01-10  5:57 ` Randy.Dunlap
2005-01-10  6:38   ` Module : " selvakumar nagendran
2005-01-10 14:48     ` Randy.Dunlap [this message]

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