[microblaze-uclinux] Mount JFFS2 returns "No such device" on existing device.

[Michael Allwright <5704634@xxxxxxxxxxx>]

G'day All

This is a question that has been going around for awhile without any 
solution, and i think its about time it was solved and posted onto the web.

The problem is related to mounting partitions in Petalinux, in this 
particular example we are running petalinux off a Spartan 3A DSP 1800a 
development board using bitstream configuration from BPI flash. The 
target partition to mount is to be formated to JFFS2 to provide a 
persistant storage for applications, config etc

The BPI flash, is a 128Mbit = 16MByte NOR parallel flash device from 
intel, and goes by the model number JS28F128J3D.

As shown below, at the current configuration stage, BPI has been 
partitioned, bitstream loaded onto mtd0, uboot loaded and configured in 
mtd1-3, and linux kernel sitting in mtd4. The system is configured and 
automatically boots straight into petalinux on power on. the target 
partition is approx 10MBytes (slight larger) located on mtd5 and is to 
be setup up with a JFFS2 file system

# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00100000 00020000 "fpga"
mtd1: 00040000 00020000 "boot"
mtd2: 00020000 00020000 "bootenv"
mtd3: 00020000 00020000 "config"
mtd4: 00400000 00020000 "image"
mtd5: 00a80000 00020000 "home"             /* JFFS2 file system here */
mtd6: 0015d000 00001000 "ROMfs"

Also shown below the output of the "cat /proc/partitions" - i don't 
think this shows much useful information.

# cat /proc/partitions
major minor  #blocks  name

 31     0       1024 mtdblock0
 31     1        256 mtdblock1
 31     2        128 mtdblock2
 31     3        128 mtdblock3
 31     4       4096 mtdblock4
 31     5      10752 mtdblock5
 31     6       1396 mtdblock6
#

auto-config has been used and the uboot recognises the partitions 
passing theses into the kernel on boot.

the JFFS2 image was build on a pc using the following command:

"mkfs.jffs2 -r ~/workspace/flashData/jffs2_image/ -o home.jffs2 -e 128 
-b --pad=10485760"

where,

"-r ~/workspace/flashData/jffs2_image/" was the source directory for the 
image containing a text file for testing purposes
"-o home.jffs2" is the output image file
"-e 128" was erase block size - set to 128 following the JS28F128J3D BPI 
datasheet specifications
"-b" for big endian format - same as the microblaze processor
"--pad=10485760" was to pad the image file up to 10Mbytes, to create a 
10Mbyte partition

I've hosted this image file for your inspection: 
http://allsey.homeip.net/uploaded%20data/home.jffs2

I have written this image to flash in a couple of ways

1. From uboot using
  tftp $(clobstart) home.jffs2
  erase $(homestart) +$(homesize)
  cp.b $(clobstart) $(homestart) 0x00A00000

- where homesize and homestart are variables i calculated and stored 
using the setenv cmd and 0x00A00000 is 10MBytes in bytes in hex.

2. In linux, using wget to download the home.jffs2 to /var directory 
(linked to RW RAMfs)
  erased partition using "eraseall /dev/mtd5"
  then attempted to use flashcp to find this is not built into the 
petalinux mtd-utils - is there any reason to why this is the case?
  from here i used "dd if=/var/home.jffs2 of=/dev/mtdblock5" instead - 
this seems to works and returns to stdout
   20480+0 records in
   20480+0 records out

Either way the main problem is when i write the command: "mount -t jffs2 
/dev/mtd5 /usr" it returns the error:
   mount: Mounting /dev/mtd5 on /usr failed: No such device

Now this error just doesn't make sense to me, i mean how is that 
writting the image and erasing seems to work fine, but come time to 
mount - it suddenly doesn't exist anymore...

the output from this next command proves that the device exists and that 
it can be accessed from the mtd-utils app eraseall - note device mtd8 
actually doesn't exist and is used for comparison.

# eraseall /dev/mtd8
eraseall: /dev/mtd8: No such device /* okay fair enough this device 
doesn't exist */
# eraseall /dev/mtd5
Erasing 128 Kibyte @ a0000 --  5 % complete. /* clearly the device exists */

Any feedback will be greatly appreciated - for further output please 
also reply and i will post back - hopefully we can get this problem 
solved once & for all.

Cheers, Michael Allwright

Mechatronics Undergrad Student
Swinburne University - Melbourne, Australia.
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