LKML Archive on
help / color / mirror / Atom feed
From: "Jörn Engel" <>
To: Stephane Chazelas <>
Cc: "Jörn Engel" <>, "Arnd Bergmann" <>,,
Subject: Re: [PATCH 2.6.24] block2mtd: removing a device and typo fixes
Date: Sat, 23 Feb 2008 16:33:21 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, 20 February 2008 17:30:53 +0000, Stephane Chazelas wrote:
> > 
> > Actually, there is /dev/mtd<x>.  Enable CONFIG_MTD_CHAR.
> Yes, my point ;). "block2mtd" creates a "mtd" out of a block
> device and "mtdchar" and "mtdblock" create the "char" and
> "block" devices out of the "mtd". This is a different concept
> from "loop". With "loop", you make a block device out of a file,
> but you do the ioctl on the target loop block device itself.
> With block2mtd, you can't do that.

The fact is that there is _no_ interface to manage mtd.  Part of the
reason is this tradition to have seperate modules every couple of lines
of code.  In other subsystems, CONFIG_MTD_CHAR would not exist and the
code always be compiled in.  Simply to get _some_ interface to handle
the device that is always there.

Without going much deeper into that discussion, I consider it acceptable
to depend on CONFIG_MTD_CHAR for things like device removal.  If you
want device removal and explicitly don't want the extra code from
mtdchar.c, send a patch or go find 500 bytes to save elsewhere. ;)

With that out of the way, the question remains which interface we should
have.  Independently of mimicking loop, I would like to have a generic
interface for all mtd, not just block2mtd.  Whether it is "echo 1 >
/sys/.../mtd/mtdN/remove" or an ioctl(), I don't care much about.

> Actually, that's what I use block2mtd for, in combination with
> "loop" to mount jffs2 filesystem images (always wondered if
> there wasn't a simpler way, BTW (other than mtdram))

Logfs can use a block device directly, which still leaves loop.
Enhancing block2mtd to work with files shouldn't be too hard.  If anyone
want a fun project to hack on...


Data dominates. If you've chosen the right data structures and organized
things well, the algorithms will almost always be self-evident. Data
structures, not algorithms, are central to programming.
-- Rob Pike

  reply	other threads:[~2008-02-23 15:34 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-12 13:47 Stephane Chazelas
2008-02-12 15:21 ` Jörn Engel
2008-02-12 16:10   ` Stephane Chazelas
2008-02-19 15:08     ` Jörn Engel
2008-02-19 22:33       ` Arnd Bergmann
2008-02-20  6:43         ` Jörn Engel
2008-02-20 14:43         ` Stephane Chazelas
2008-02-20 16:30           ` Jörn Engel
2008-02-20 17:02             ` Stephane Chazelas
2008-02-20 17:22               ` Jörn Engel
2008-02-20 17:30                 ` Stephane Chazelas
2008-02-23 15:33                   ` Jörn Engel [this message]
2008-02-20 14:36       ` Stephane Chazelas
2008-02-20 16:42         ` Jörn Engel
2008-02-20 16:55           ` Stephane Chazelas

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \
    --subject='Re: [PATCH 2.6.24] block2mtd: removing a device and typo fixes' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).