linux-kernel - Re: [patch] remove artificial software max

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Message-ID: <460FE380.2050608@slax.org>
Date:	Sun, 01 Apr 2007 18:53:20 +0200
From:	Tomas M <tomas@...x.org>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [patch] remove artificial software max_loop limit

Andrew Morton wrote:
> On Fri, 30 Mar 2007 02:25:37 -0700
> "Ken Chen" <kenchen@...gle.com> wrote:
> 
>> -module_param(max_loop, int, 0);
>> -MODULE_PARM_DESC(max_loop, "Maximum number of loop devices (1-256)");
> 
> So..  this change will cause a fatal error for anyone who is presently
> using max_loop, won't it?  If they're doing that within their
> initramfs/initrd/etc then things could get rather ugly for them.

I consider myself the most precious user of max_loop.

The max_loop parameter would cause a fatal error only in the case if you 
modprobe loop manually, for example:

  $ modprobe loop max_loop=200

But people don't usually use this, read below.

> I don't know how much of a problem this will be in practice - do
> people use max_loop much?

yes, but no as a module parameter.

People usually use max_loop as a 'kernel boot parameter' passed in 
APPEND section in a boot loader (such as LILO for example), not as a 
parameter for module in initrd. Why? Because it's easier; people are 
lazy, people compile loop.c into kernel so they don't need to update the 
loop.ko module in initrd every time a new Kernel is released.

I believe that IF you _really_ need to preserve the boot parameter, then 
the parameter should _not_ be ignored, rather it should have the same 
function like before - to limit the loop driver so if you use 
max_loop=10 for example, it should not allow loop.c to create more than 
10 loops.

And if no parameter is used at all, there will be unlimited amount of 
loops. Simply clever :)

This will make it _completely_ backward-compatible, with very small code 
change I guess.

Just my two cents.

Thank you for reading so far.

Tomas M
slax.org

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