**************     NOTE     *********************
This procedure is now obsolete (since 25 Sep '12)
Use the new one found in 
https://github.com/Renesas-EMEV2/RenesasEV2-bootloader
Find testsd.sh in "README-Renesas" 
*************************************************

How to build a bootable SD card for the Renesas tablet

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1) On your Linux host PC (tested on my Ubuntu 11.10 64-bit)

1.1) Place somewhere these files (out of a stock firmware, or a new build):

 android-fs4.tar.gz
 uImage4

E.g. copy them in ./tmp (refer to this path later)

1.2) Modify ./init.rc inside android-fs4.tar.gz, so that it'll mount the partitions we're going to create on the SD card, i.e.:

...
on fs
   mount ext3 /dev/block/mmcblk1p6 /mnt/sdcard nosuid nodev
   mount ext3 /dev/block/mmcblk1p5 /data nosuid nodev
...

1.3) Insert a 2Gb SD card on your PC (through a USB card reader, or whatever).
1.4) Note what new device is created for the SD card. It's "/dev/sdd" in my case.
1.5) Create the bootable SD card executing:

sudo ./part_sd.sh /dev/sdd
sudo ./create_bootsd.sh /dev/sdd ./tmp

NOTES 

- The SD card content is going to be erased completely.
- Cards larger than 2Gb aren't accepted by Rena bootloader. 
- The "part_sd.sh" script should be modified for cards smaller than 2Gb.
- "part_sd.sh" is required only once, to create the partitoning scheme on the SD card:

# p1 500MB	: 	boot files
# p2 256KB	:	uboot environment
# p3 400MB	:	android-fs
# p4		:	EXTENDED
# p5 750MB	:	data-fs / cache
# p6 the rest	:	nand-fs

As you have the SD partioned like that, you can run and re-run ./create_bootsd.sh multiple times, to update the SD content.


2) On your Renesas tablet (tested on mine "second version"):

2.1) Insert the bootable SD card into tablet.
2.2) Boot with Vol+&Power (as if you were updating firmware; but this is NOT doing that).
2.3) Be patient! It takes couple minutes to get to the Android home screen. First time even longer.

To start the original NAND firmware, just shutdown and restart with the Power button as usual.

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Known Issues

1) Overall device response is slower than that with internal NAND.
That's also a clue about what the final performance comes from...

2) On second boot from SD, seems like not working... To be investigated about.

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Technical details

If you wish to discover how our bootloader works, have a look at the README-Renesas in https://github.com/f...sEV2-bootloader

The uboot-sd.bin has been hex-edited to patch the boot commands, so to start the root file system to the SD card partition, I.e.

bootcmd=run ext3cmd
ext3_root=/dev/mmcblk1p3
cfg_ddr=mem=129M@0x40000000 mem=256M@0x50000000
ext3cmd=setenv bootargs root=$(ext3_root) noinitrd init=/init console=ttyS0,115200n8n SELINUX_INIT=no $(cfg_ddr) rw video=qfb: ip=none rootfstype=ext3 rootwait;bootm 40007fc0

The init.rc has been modified to mount the SD card partitions, in place of the NAND ones.

The vold.conf and vold.fstab content has been commented out as well, to remove the use of an external SD card (which is of course absent).