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From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Pierre Ossman <drzeus-list@drzeus.cx>
Cc: linux-kernel@vger.kernel.org
Subject: Re: MMC block major dev
Date: Tue, 31 Aug 2004 20:15:56 +0100	[thread overview]
Message-ID: <20040831201556.B11053@flint.arm.linux.org.uk> (raw)
In-Reply-To: <4134CDF0.7070600@drzeus.cx>; from drzeus-list@drzeus.cx on Tue, Aug 31, 2004 at 09:13:52PM +0200

On Tue, Aug 31, 2004 at 09:13:52PM +0200, Pierre Ossman wrote:
> It seems that the MMC block layer hasn't been assigned a major number. 
> The code registers the block dev with a uninitialized variable. It then 
> proceeds to create a mmc dir under devfs. Since I'm not using devfs this 
> then poses a problem.

First, "uninitialised variables" is a misdescription here.  Variables
declared outside the scope of functions are _always_ initialised even
though there is no apparant assignment.

They're placed in the BSS, or "zero initialised" section.  They have
a well defined value.  Zero.

Registering with the block layer with a major number of zero means
"find me a free major number and assign that to me."  This is nothing
new.  If devfs can't cope with that, devfs is buggy.  Use udev instead.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core

  reply	other threads:[~2004-08-31 19:26 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-08-31 19:13 MMC block major dev Pierre Ossman
2004-08-31 19:15 ` Russell King [this message]
2004-08-31 19:47   ` Pierre Ossman
2004-09-01 12:16     ` Alan Cox
2004-09-01 21:55       ` Russell King
2004-09-01 21:28         ` Alan Cox
2004-09-01 12:18 ` Alan Cox

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