Loading JFFS2 Images Onto a Board
Contents
Background
Journalling Flash File System version 2, or JFFS2, is a log-structured file system used on flash memory devices. JFFS2 images are typically created on a development PC and deployed to an embedded target using TFTP commands from the target's bootloader. Deployment requires both serial and Ethernet connections to the board along with a TFTP server set up on a development machine.
For instructions on installing a TFTP server on a development PC: Installing TFTP server
For details on connecting to the serial port for an embedded target: Serial Connections
JFFS2 file systems are available for download on EMAC's FTP site.
For instructions on creating a JFFS2 file system image see the following page: Creating JFFS2 Images
General Information
The section below provides links and useful information for performing JFFS2 programming using U-Boot and Redboot. The links provide pages with the generic procedures for programming EMAC modules based on the bootloader type.
Using U-Boot
Refer to the following pages for instructions on accessing U-Boot on the serial console:
U-Boot Overview
Loading Images with U-Boot
From the U-Boot prompt it is possible to set the target's IP address dynamically using DHCP:
U-Boot> set autoload no
U-Boot> dhcp
The target's IP can also be manually set using the ipaddr environment variable as follows:
U-Boot> set ipaddr 192.168.0.101
Once the target IP is set, the TFTP server's IP address must be specified:
U-Boot> set serverip 192.168.0.100
The configuration of the bootloader environment can be checked at any time using the printenv command. As described in Loading Images with U-Boot, the JFFS2 image will then be loaded into SDRAM and programmed into flash. A full example for the SoM-9G45 will be provided below.
Full Example Using U-Boot (SoM-9G45)
This section provides a detailed example of loading a JFFS2 file system onto the SoM-9G45 and shows how U-Boot responds to the various commands when performed successfully.
U-Boot 2009.06-rc1-svn1786 (Nov 28 2011 - 17:22:29)
EMAC Inc. SOM-9M10/G45M
I2C: ready
DRAM: 128 MB
NAND: 256 MiB
DataFlash:AT45DB321
Nb pages: 8192
Page Size: 528
Size= 4325376 bytes
Logical address: 0xC0000000
Area 0: C0000000 to C00041FF (RO) Bootstrap
Area 1: C0004200 to C00083FF Environment
Area 2: C0008400 to C0041FFF (RO) U-Boot
Area 3: C0042000 to C0251FFF Kernel
Area 4: C0252000 to C041FFFF FS
In: serial
Out: serial
Err: serial
Net: macb0
macb0: Starting autonegotiation...
macb0: Autonegotiation complete
macb0: link up, 100Mbps full-duplex (lpa: 0xcde1)
Hit any key to stop autoboot: 0
U-Boot> set autoload no
U-Boot> dhcp
macb0: link up, 100Mbps full-duplex (lpa: 0xcde1)
BOOTP broadcast 1
DHCP client bound to address 10.0.2.221
U-Boot> set serverip 10.0.2.168
U-Boot> tftp 0x74000000 som-9g45m-rootfs.jffs2
macb0: link up, 100Mbps full-duplex (lpa: 0xcde1)
Using macb0 device
TFTP from server 10.0.2.168; our IP address is 10.0.2.221
Filename 'som-9g45m-rootfs.jffs2'.
Load address: 0x74000000
Loading: #################################################################
...
####################################################
done
Bytes transferred = 27473444 (1a33624 hex)
U-Boot> nand erase
NAND erase: device 0 whole chip
Skipping bad block at 0x03320000
Skipping bad block at 0x079e0000
Skipping bad block at 0x085e0000
Erasing at 0xffe0000 -- 100% complete.
OK
U-Boot> nand write.jffs2 0x74000000 0x0 ${filesize}
NAND write: device 0 offset 0x0, size 0x1a33624
NAND write: Padding to page size...
27473444 bytes written: OK
U-Boot>
Quick Reference (By Target Type)
This section provides a quick reference for programming various targets with a JFFS2 image. It is assumed that the Ethernet setup is performed as described above in the General Information section.
SoM-9260M
U-Boot> tftp 0x20000000 som-9260m-rootfs.jffs2
U-Boot> protect off all
U-Boot> erase 0x10400000 0x11ffffff
U-Boot> cp.b 0x20000000 0x10400000 ${filesize}
# Erase the second bank for 64Mb modules
U-Boot> erase 0x12000000 0x13ffffff
# OE 4 - set filesystem read/write on first boot
U-Boot> setenv bootargs 'console=ttyS3,115200 root=/dev/mtdblock3 rootfstype=jffs2 rw'
SoM-9G20M
U-Boot> tftp 0x20000000 som-9g20m-rootfs.jffs2
U-Boot> nand erase
U-Boot> nand write.jffs2 0x20000000 0x0 ${filesize}
SoM-9G45M
U-Boot> tftp 0x74000000 som-9g45m-rootfs.jffs2
U-Boot> nand erase
U-Boot> nand write.jffs2 0x74000000 0x0 ${filesize}
SoM-9M10M
U-Boot> tftp 0x74000000 som-9m10m-rootfs.jffs2
U-Boot> nand erase
U-Boot> nand write.jffs2 0x74000000 0x0 ${filesize}
