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Message-ID: <096201c18418$07d86bf0$5601010a@prefect>
From: "Bradley D. LaRonde" <brad@ltc.com>
To: <linux-kernel@vger.kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
In-Reply-To: <20011213160007.D998D23CCB@persephone.dmz.logatique.fr> <9vb3k4$9kj$1@cesium.transmeta.com>
Subject: Re: Mounting a in-ROM filesystem efficiently
Date: Thu, 13 Dec 2001 15:52:08 -0500
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----- Original Message -----
From: "H. Peter Anvin" <hpa@zytor.com>
To: <linux-kernel@vger.kernel.org>
Sent: Thursday, December 13, 2001 3:38 PM
Subject: Re: Mounting a in-ROM filesystem efficiently


> Followup to:  <20011213160007.D998D23CCB@persephone.dmz.logatique.fr>
> By author:    Thomas Capricelli <orzel@kde.org>
> In newsgroup: linux.dev.kernel
>
> > Ideally, i would give address/length of the fs in ROM to a function, and
I
> > would get a ramdisk configured to read its data exactly there, and not
in
> > ram.
>
> The right thing for you to do is to write a block device driver, and
> then mount that block device like any order device.  Your in-use data
> will be copied to RAM (i.e. cached), but it can be dropped and
> re-fetched as necessary.  This should be the desired behaviour.

That's one way (q.v. MTD block device), but it adds an unecessary block
layer.

The cramfs patch I mentioned shuns the block layer and instead allows the fs
to read directly from ROM.

Regards,
Brad