howto boot kernel from ubi volume?

From: "Lambrecht Jürgen" <J.Lambrecht@TELEVIC.com>
To: "barebox@lists.infradead.org" <barebox@lists.infradead.org>
Subject: howto boot kernel from ubi volume?
Date: Wed, 28 Sep 2011 10:32:02 +0200	[thread overview]
Message-ID: <4E82DB82.2000505@televic.com> (raw)

Hello,

Because a NAND flash is not reliable, I don't want to write the kernel 
image raw to flash.
Instead, I want to put it in an UBI volume.

* The currently running kernel is written in barebox to 
/dev/nand0.kernel.bb, and the ubi rootfs image to /dev/nand0.root.bb; I 
have a free partition in /dev/nand0.diag.bb.
* So I in a running kernel (v3.0-rc6) I formatted an ubi partition (on 
that nand0.diag.bb mtd3), and created 2 volumes (kernel and rootfs). 
Then I tftp'd a zImage to the kernel volume - the same zImage that is 
currently running.
* Then in barebox: 'barebox:/dev ubiattach nand0.diag' gives:
UBI: attaching mtd0 to ubi0
UBI: physical eraseblock size:   131072 bytes (128 KiB)
UBI: logical eraseblock size:    129024 bytes
UBI: smallest flash I/O unit:    2048
UBI: sub-page size:              512
UBI: VID header offset:          512 (aligned 512)
UBI: data offset:                2048
registering /dev/ubi0
registering kernel as /dev/ubi0.kernel
registering rootfs as /dev/ubi0.rootfs
UBI: attached mtd0 to ubi0
UBI: MTD device name:            "nand0.diag"
UBI: MTD device size:            48 MiB
UBI: number of good PEBs:        384
UBI: number of bad PEBs:         0
UBI: max. allowed volumes:       128
UBI: wear-leveling threshold:    4096
UBI: number of internal volumes: 1
UBI: number of user volumes:     2
UBI: available PEBs:             3
UBI: total number of reserved PEBs: 381
UBI: number of PEBs reserved for bad PEB handling: 3
UBI: max/mean erase counter: 19/0
* Then I set bootargs correct
* Then 'barebox:/dev bootz ubi0.kernel' gives:
ubi_volume_cdev_read: 48 @ 0x00000000
invalid magic 0x0001f800

Why is that?
My barebox version is 2010.12.0.
Could it be because the mtd-utils used in linux is 1.4.6 (both on the 
target and the host (my laptop)), and the one in barebox is older?

FYI: When I create an empty ubi volume in linux, and try to tftp to it 
in barebox, I get this error:
(and the same error with ubimkvol)

barebox:/ tftp zImage /dev/ubi0.kernel
error frame: 0xa3b05828 0x00000882
TFTP from server 10.0.56.4 ('zImage' -> '/dev/ubi0.kernel')
         UBI error: ubi_io_write: error -5 while writing 512 bytes to 
PEB 0:512, written 0 bytes
UBI warning: ubi_eba_write_leb: failed to write VID header to LEB 
2147479551:0, PEB 0
UBI: try another PEB
UBI error: ubi_io_write: error -5 while writing 512 bytes to PEB 0:512, 
written 0 bytes
UBI warning: ubi_eba_write_leb: failed to write VID header to LEB 
2147479551:0, PEB 0
UBI: try another PEB
UBI error: ubi_io_write: error -5 while writing 512 bytes to PEB 0:512, 
written 0 bytes
UBI warning: ubi_eba_write_leb: failed to write VID header to LEB 
2147479551:0, PEB 0
UBI: try another PEB
UBI error: ubi_io_write: error -5 while writing 512 bytes to PEB 0:512, 
written 0 bytes
UBI warning: ubi_eba_write_leb: failed to write VID header to LEB 
2147479551:0, PEB 0
UBI warning: ubi_ro_mode: switch to read-only mode
Cannot start volume update
write: Read-only file system
\
tftp failed: error -30

Kind regards,
Jürgen

Jürgen Lambrecht
R&D Associate
Tel: +32 (0)51 303045    Fax: +32 (0)51 310670
http://www.televic-rail.com
Televic Rail NV - Leo Bekaertlaan 1 - 8870 Izegem - Belgium
Company number 0825.539.581 - RPR Kortrijk

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