linux-kernel - Re: Can initramfs be mounted read-only?

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Message-ID: <9b2b86520908121424qff7443fn84d07fb8dff7c863@mail.gmail.com>
Date:	Wed, 12 Aug 2009 22:24:16 +0100
From:	Alan Jenkins <sourcejedi.lkml@...glemail.com>
To:	David Wuertele <dave+gmane@...rtele.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Can initramfs be mounted read-only?

On 8/12/09, David Wuertele <dave+gmane@...rtele.com> wrote:
> I've been trying to create a system with a read-only rootfs using initramfs,
> but I'm not having any luck.  I've included "ro" on my command line and when
> I cat /proc/cmdline it reports "ro" like I expect.  But when I type "mount",
> I see this:
>
>   rootfs on / type rootfs (rw)

Changing this could potentially break a lot of systems.  At least
Debian has "ro" as a default boot option, and it uses an initramfs by
default.

> And I can create new files and write to them just fine.  Is it possible to
> mount an initramfs read-only?
>
> The documentation for early userspace and initramfs does not talk about
> read/write permissions.

Have you tried running "mount / -oremount,ro" in an init script?

Regards
Alan
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