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Message-ID: <aec7e5c305041103154461ac5c@mail.gmail.com>
Date: Mon, 11 Apr 2005 12:15:08 +0200
From: Magnus Damm <magnus.damm@gmail.com>
Reply-To: Magnus Damm <magnus.damm@gmail.com>
To: Domen Puncer <domen@coderock.org>
Subject: Re: [PATCH 0/5] autoparam
Cc: Magnus Damm <damm@opensource.se>, linux-kernel@vger.kernel.org
In-Reply-To: <20050409182128.GA5542@nd47.coderock.org>
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	 <20050409182128.GA5542@nd47.coderock.org>
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On 4/9/05, Domen Puncer <domen@coderock.org> wrote:
> On 21/03/05 00:06 +0100, Magnus Damm wrote:
> > Here are a set of patches that makes it possible to autogenerate kernel command
> > line documentation from the source code. The approach is rather straightforward
> > - the parameter name, the type and the description are stored in a section
> > called __param_strings. After vmlinux is built this section is extracted using
> > objcopy and a script is used to generate a primitive - but up to date -
> > document.
> 
> I think it's a great idea. A needed feature with simple implementation.
> I like it.

Thanks! And together with the "disable built-in" patch we have a much
more user-friendly system...

> > Right now the section is left in the kernel binary. The document is currently
> > not generated from the Makefile, so the curious user should perform:
> 
> Any plans to make this a complete patch?

Yes, if there is enough interest. I think autogenerating documents
from source code is the right way to do it, but I am not sure about
the disadvantages. Maybe someone could enlighten me? The latest patch
does not support obsolete MODULE_PARM() parameters - so I need to add
that to next release but that is no biggie.

> > $ objcopy -j __param_strings vmlinux -O binary foo
> > $ chmod a+x scripts/section2text.rb
> > $ cat foo | ./scripts/section2text.rb
> >
> > And yeah, you need to install ruby to run the script.
> 
> Attached a perl script, that has almost the same output. (I think
> perl is more usual on linux machines)

Great, thanks! I prefer to do prototype hacking in ruby, but I realize
that "the magic duct tape language" is more suitable.. =)

Also, I am thinking of using a prefix with the parameter type to
determine the origin of the parameter, ie:

prefix "s:" means from __setup()
prefix "e:" means from early_param()
prefix "m:" means from module_param()
prefix "o:" means from obsolete MODULE_PARM()

Then I would like to let the script convert the types to a common set of types.
I thought about treating descriptions without parameters as errors,
and generate warnings about parameters without description. And to
reduce the amount of warnings I think it is a good idea to add a
SETUP_DESC() as suggested by Matt Domsch.

> > The ruby script section2text.rb does some checks to see if MODULE_PARM_DESC()
> > is used without module_param(). You will find interesting typos.
> >
> > Future work that extends this idea could include replacing __setup(name) with
> > __setup(name, descr). And storing the documentation somewhere to make it easy
> > for the end user to look up the generated parameter list from the boot loader.
> 
> And kernel-parameters.txt will never again have obsoleted options :-)

Exactly! =)

/magnus
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