[Buildroot] need smaller filesystem for NOR

[John Stile <john@stilen.com>]

On Mon, 2013-02-11 at 16:19 -0800, John Stile wrote:
> On Fri, 2013-02-08 at 13:34 -0800, John Stile wrote:
> > Dear Thomas Petazzoni,
> > 
> > On Fri, 2013-02-08 at 18:38 +0100, Thomas Petazzoni wrote:
> > > Dear John Stile,
> > > 
> > > On Fri, 08 Feb 2013 09:25:17 -0800, John Stile wrote:
> > > > I primarily boot from one of two 128Mb NAND areas, but I have an 8Mb NOR
> > > > failsafe if NAND is bad.  I have about 5.5Mb available for the
> > > > Filesystem after loading at91bootstrap, uboot, uboot-env, and kernel.
> > > > ...(using buildroot-2011.11)...
> > > > 
> > > > The rootfs.jffs2 for NAND is 41Mb.
> > > > I need one for NOR that is less than 5.5Mb.
> > > > 
> > > > Is there a good method or script to copy buildroot's rootfs.jffs2  to
> > > > make a smaller copy for NOR?
> > > > 
> > > > My first attempt  leads to
> > > > VFS: Mounted root (jffs2 filesystem) on device 31:1.
> > > > Freeing init memory: 104K
> > > > Warning: unable to open an initial console.
> > > > Kernel panic - not syncing: No init found.  Try passing init= option to kernel.
> > > > [<c0028678>] (unwind_backtrace+0x0/0xdc) from [<c0243990>] (panic+0x34/0x110)
> > > > [<c0243990>] (panic+0x34/0x110) from [<c002254c>] (init_post+0x138/0x170)
> > > > [<c002254c>] (init_post+0x138/0x170) from [<c0008408>] (kernel_init+0xbc/0xe8)
> > > > [<c0008408>] (kernel_init+0xbc/0xe8) from [<c003b634>] (do_exit+0x0/0x5a4)
> > > > [<c003b634>] (do_exit+0x0/0x5a4) from [<00000003>] (0x3)
> > > > 
> > > > I think this means the file system is found and mounted, and for some
> > > > reason, init isn't found, although I have played with init= to no avail,
> > > > and if I mount my little jffs2, I do see busybox and all the links
> > > > (/bin/init).
> > > 
> > > Beware that if a NAND or NOR partition is empty and properly erase,
> > > jffs2 will happily mount it and show a filesystem that contains no
> > > file. So the behavior you're seeing here could perfectly happen if your
> > > NAND or NOR partition is simply empty.
> > 
> > To check for an empty file system I compared the hex dump of my jffs2
> > image to the contents of NOR, and they are the same.
> > From the uboot prompt I ran: md.b 0xD0294000 0x19
> > From the shell I ran: od -t x1z NORrootfs.jffs2
> > Both are identical, and I can mount my .jffs2 and see it contains stuff.
> > 
> > Could it be my bootargs mtdparts pointing to the wrong place?
> > bootargs=mem=64M console=ttyS0,115200 mtdparts=dataflash0:2640k(bootstrap/uboot/env/kernel)ro,-(rootfs) root=/dev/mtdblock1 rw rootfstype=jffs2
> > 
> > I also tried exchanging 'dataflash0' for 'dataflash1', with no change in
> > behavior.
> > 
> > This is the first time I have tried to put a file system on NOR.
> > 
> 
> I discovered the kernel mtdparts statement to control the mtd partition
> layout, which I guess is a good staring point for mounting the root file
> system, but I still can't mount.
> 
> I gleaned the information from the kernel boot messages and the kernel
> drivers/mtd/devices/at91_dataflash.c.
> 
> Default kernel boot messages for NAND and NOR:
>  NAND device: Manufacturer ID: 0x2c, Chip ID: 0xda (Micron NAND 256MiB 3,3V 8-bit)
>  AT91 NAND: 8-bit, Software ECC
>  Scanning device for bad blocks
>  mtd: no mtd-id
>  Creating 3 MTD partitions on "atmel_nand":
>  0x000000000000-0x000000400000 : "Bootstrap"
>  0x000000400000-0x000004000000 : "Partition 1"
>  0x000004000000-0x000010000000 : "Partition 2"
>  atmel_spi atmel_spi.0: Atmel SPI Controller at 0xfffc8000 (irq 12)
>  mtd_dataflash spi0.1: AT45DB642x (8448 KBytes) pagesize 1056 bytes (OTP)
> 
> I changed my boot args to:
> bootargs=mem=64M console=ttyS0,115200 mtdparts=spi0.1-AT45DB642x:2640k(bootstrap/env/uboot/kernel)ro,-(rootfs);atmel_nand:128k(bootstrap1)ro,256k(uboot1)ro,128k(env1)ro,1536K(unused),2M(linux1),124M(rootfs1),128k(bootstrap2)ro,256k(uboot2)ro,128k(env2)ro,1536k(unused2),2M(linux2),124M(rootfs2) root=/dev/mtdblock2 rw rootfstype=jffs2
> 
> Now kernel boot messages for NAND and NOR show my partitions, but fail
> to find the root filesystem:
>  NAND device: Manufacturer ID: 0x2c, Chip ID: 0xda (Micron NAND 256MiB 3,3V 8-bit)
>  AT91 NAND: 8-bit, Software ECC
>  Scanning device for bad blocks
>  12 cmdlinepart partitions found on MTD device atmel_nand
>  Creating 12 MTD partitions on "atmel_nand":
>  0x000000000000-0x000000020000 : "bootstrap1"
>  0x000000020000-0x000000060000 : "uboot1"
>  0x000000060000-0x000000080000 : "env1"
>  0x000000080000-0x000000200000 : "unused"
>  0x000000200000-0x000000400000 : "linux1"
>  0x000000400000-0x000008000000 : "rootfs1"
>  0x000008000000-0x000008020000 : "bootstrap2"
>  0x000008020000-0x000008060000 : "uboot2"
>  0x000008060000-0x000008080000 : "env2"
>  0x000008080000-0x000008200000 : "unused2"
>  0x000008200000-0x000008400000 : "linux2"
>  0x000008400000-0x000010000000 : "rootfs2"
>  atmel_spi atmel_spi.0: Atmel SPI Controller at 0xfffc8000 (irq 12)
>  mtd_dataflash spi0.1: AT45DB642x (8448 KBytes) pagesize 1056 bytes (OTP)
>  2 cmdlinepart partitions found on MTD device spi0.1-AT45DB642x
>  Creating 2 MTD partitions on "spi0.1-AT45DB642x":
>  0x000000000000-0x000000294000 : "bootstrap/env/uboot/kernel"
>  0x000000294000-0x000000840000 : "rootfs"
> ...
>  rtc-at91sam9 at91_rtt.0: hctosys: unable to read the hardware clock
>  jffs2: Too few erase blocks (1)
>  List of all partitions:
>  1f00             128 mtdblock0 (driver?)
>  1f01             256 mtdblock1 (driver?)
>  1f02             128 mtdblock2 (driver?)
>  1f03            1536 mtdblock3 (driver?)
>  1f04            2048 mtdblock4 (driver?)
>  1f05          126976 mtdblock5 (driver?)
>  1f06             128 mtdblock6 (driver?)
>  1f07             256 mtdblock7 (driver?)
>  1f08             128 mtdblock8 (driver?)
>  1f09            1536 mtdblock9 (driver?)
>  1f0a            2048 mtdblock10 (driver?)
>  1f0b          126976 mtdblock11 (driver?)
>  1f0c            2640 mtdblock12 driver: mtd_dataflash
>  1f0d            5808 mtdblock13 driver: mtd_dataflash
>  No filesystem could mount root, tried:  jffs2
>  Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(31,2)
> 
> ORDER in mtdparts does not matter (NAND always before NOR)?
> 
> Next I changed from:
>  root=/dev/mtdblock2
> to:
>  root=/dev/mtdblock 13
> 
> The kernel messages now show my desire layout at boot time, however, the
> the file system still does not mount, but the root file system is not
> found.
> 
> Kernel boot messages for NAND and NOR:
>  ... 
>  rtc-at91sam9 at91_rtt.0: hctosys: unable to read the hardware clock
>  JFFS2 write-buffering enabled buffer (1056) erasesize (8448)
>  Node at 0x00001cd8 with length 0x00000489 would run over the end of the erase block
>  Perhaps the file system was created with the wrong erase size?
>  jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00001cdc: 0x0489 instead
>  jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00001ce0: 0x651a instead
>  jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00001ce4: 0x0006 instead
>  ...
>  Further such events for this erase block will not be printed
>  VFS: Mounted root (jffs2 filesystem) on device 31:13.
>  Freeing init memory: 104K
>  Kernel panic - not syncing: Attempted to kill init!
>  [<c0028678>] (unwind_backtrace+0x0/0xdc) from [<c0243990>] (panic+0x34/0x110)
> 
> I think this means I am close.
> 
> Next I tried to edit my jffs options in the .config for my recovery
> 'failsafe' buildroot:
> Filesystem images  --->
>  [*] jffs2 root filesystem
>  Flash Type (Select custom page and erase size)  --->
>  (0x1065) Page Size
>  (0xC60) Erase block size
> 
> I gleaned these numbers from the output o the sam-ba utility used to
> load the NOR flash, but they still don't work.
> 
> This had no effect.
> 
I solved my problem.
I had to find the correct flash setting for jffs2.
This sent me in the right direction:
    http://www.at91.com/forum/viewtopic.php/f,9/t,4983/

Filesystem images  --->
 [*] jffs2 root filesystem
 Flash Type (AT45 dataflash with 1056 byte pagesize)

I am using a separate buildroot config (per Thomas Petazzoni's advice).
Thank you.