On 16/12/2014 11:23, Gergely Kiss wrote:
Hi Rafał,
please allow me to comment on your 2nd point as I was the one who
recently published the patch to make extroot functionality work with
UBIFS.
"It seems that if there isn't "rootfs" MTD partition,
then the code will look for "rootfs" UBI volume. The same applies to
the "rootfs_data"."
That's correct.
"But what if my serial flash contains "rootfs" + "rootfs_data"
partitions and I still want to use some UBI volume on another flash
(NAND one)?"
I'm not sure I understand what you mean here. Are there any devices
out there with multiple flash chips on-board? As far as I know, UBI
cannot work on top of block devices (eg. USB flashes, SD cards), only
raw flash chips so I can't really imagine what exact use-case you
mean. Could you please clarify?
Thanks,
Gergely
On 16 December 2014 at 11:00, Rafał Miłecki <zaj...@gmail.com> wrote:
I've spent few hours today trying to understand extroot. I've failed :(
Of course I was trying to use wiki pages:
http://wiki.openwrt.org/doc/howto/extroot
http://wiki.openwrt.org/doc/uci/fstab
1) Main question
Is the following sentence true at all?
The configuration of extroot is very simple and is done entirely in
/etc/config/fstab.
It seems that /etc/init.d/fstab uses "block umount" and "block mount"
only. I was reading the source code (fstools-2014-12-15/block.c) and
it seems that "block mount" doesn't really handle extroot at all.
I think some kind of extroot support is provided in "block extroot",
but I don't fully understand it. It seems to be looking for partitions
"rootfs" and then "rootfs_data" ignoring whatever is set in
/etc/config/fstab. If "mount extroot" is really supposed to be used,
is there any way to point some external device (without MTD
partitions) as extroot? I got confused.
2) UBI and UBIFS support
I guess it's too new to be documented and I don't understand it much
from the code. It seems that if there isn't "rootfs" MTD partition,
then the code will look for "rootfs" UBI volume. The same applies to
the "rootfs_data".
But what if my serial flash contains "rootfs" + "rootfs_data"
partitions and I still want to use some UBI volume on another flash
(NAND one)?
--
Rafał
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Hi,
I think this is where this discussion started and Rafal explains a
bit more about the hardware:
https://lists.openwrt.org/pipermail/openwrt-devel/2014-December/029717.html
Regards,
Flavio
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