[Gta04-owner] [gta04-uboot][PATCH] boot.txt: use better rootfstype value

Martin Jansa martin.jansa at gmail.com
Mon Apr 23 22:57:01 CEST 2012


On Mon, Apr 23, 2012 at 10:31:18PM +0200, Dr. H. Nikolaus Schaller wrote:
> 
> Am 23.04.2012 um 22:18 schrieb Martin Jansa:
> 
> > On Mon, Apr 23, 2012 at 10:05:10PM +0200, Dr. H. Nikolaus Schaller wrote:
> >> Hi Martin,
> >> thanks for the patch.
> >> 
> >> I am trying to understand it - but where is it documented that
> >> the rootfstype allows a comma separated list? I am not sure if
> >> all kernels support this.
> > 
> > linux/Documentation/kernel-parameters.txt says just:
> > rootfstype= [KNL] Set root filesystem type
> 
> that was what I found and made me wondering.
> 
> > 
> > but
> > http://tldp.org/HOWTO/BootPrompt-HOWTO-3.html
> > The `rootfstype=' Argument
> > 
> > This option allows you to give a comma separated list of fs types that
> > will be tried for a match when trying to mount the root filesystem. This
> > list will be used instead of the internal default which usually starts
> > with ext2, minix and the like.
> > 
> > and
> > init/do_mounts.c in kernel confirms that comma separated list was
> > supported already in Linux-2.6.12-rc2 and probably even before.
> 
> Ok, then I think it is safe to apply the patch. We might then even
> add ext2 for convenience at the end of the list since I assume the
> first successful fs ends scanning the list.

ext4 and ext3 as fs "drivers" can mount ext2 fs just fine, so such
option would be used only on kernel image with both ext4 and ext3
diabled or as modules.

> > Not many defconfigs in kernel are using list of filesystems, but in this
> > case no rootfstype param would be better then just ext3.
> 
> The reason seems to be (we have inherited from the BeagleBoard) that
> it should be some ext if we boot from SD card and jffs2/ubifs if we boot
> from NAND. These should not be tried on a SD card. WIth the same
> kernel image which may e.g. always comes from NAND or SD card.

Right, without rootfstype specified it will try filesystems in order how
they register themselves which I'm not sure will make ext* before
jffs2/ubifs or after (maybe causing few ms delay from unsuccessful mount).

Cheers,

-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa at gmail.com
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