[FAQ] TDA4VM: Flashing the tiny rootfs image using UNIFLASH on OSPI

Hi Pouyan,

Assuming that you have SD card interface available.

-1- Get the tiny file system

Please find the attached tiny file system: /cfs-file/__key/communityserver-discussions-components-files/791/6708.tisdk_2D00_tiny_2D00_image_2D00_j7_2D00_evm.tar.xz

Or alternatively generate the same using the following instructions:

git clone git://arago-project.org/git/projects/oe-layersetup.git tisdk
cd tisdk/
 
# Copy config file from the 7.00 installer yocto-build/configs/psdkla/psdkla-07_00_00.txt
./oe-layertool-setup.sh -f psdkla-07_00_00.txt
 
# export proxy
export ftp_proxy=http://webproxy.ext.ti.com:80
export http_proxy=http://webproxy.ext.ti.com:80
export https_proxy=http://webproxy.ext.ti.com:80
 
cd build
# Edit config file if you want to reuse downloads folder
vi conf/local.conf
. conf/setenv
 
# this is the path to the toolchains for ARMv7 and ARMv8
TOOLCHAIN_BASE=/sdk/tools MACHINE=j7-evm bitbake -k tisdk-tiny-image
 
# build image can be found here
la -la tisdk/build/arago-tmp-external-arm-glibc/deploy/images/j7-evm/tisdk-tiny-image-j7-evm.tar.xz

-2- Flash the tiny file system to the UBI partition of OSPI

We will use this image to flash to the UBI partition of OSPI. Instructions in section Using UBIFS on flash of https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/07_00_01_01/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/QSPI.html

Follow below steps once you have the tisdk-tiny-image-j7-evm.tar.xz:

# boot to file system using SD card

cat /proc/mtd
ubiformat /dev/mtd6
ubiattach -p /dev/mtd6
ubimkvol /dev/ubi0 -N flash_fs -s 55MiB
mkdir /mnt/flash
mount -t ubifs ubi0:flash_fs /mnt/flash/

cd /mnt/flash
tar xvf /home/root/tisdk-tiny-image-j7-evm.tar.xz
sync

cd /home/root/
umount /mnt/flash

# flashing completes here

NOTE that we haven't still flashed the kernel image and DTB to the tiny image, we need to pick this from TFTP or SD card while booting from OSPI UBIFS.

NOTE We are not flashing the Kernel Image and DTB to this as then u-boot needs to read the Image and DTB from the UBIFS and currently there is an issue when u-boot tries to open and read the UNIFS. To work around this we provide the Kernel Image and DTB to the u-boot.

-3- Update u-boot environment to support UBIFS

Also, the u-boot environment needs to be modified according to the below to enable UBI FS (this is not part of the SDK, hence the additional steps)

diff --git a/include/configs/j721e_evm.h b/include/configs/j721e_evm.h
index edf747b8d3..9d5b7452ca 100644
--- a/include/configs/j721e_evm.h
+++ b/include/configs/j721e_evm.h
@@ -82,6 +82,14 @@
                "${mtdparts}\0"                                         \
        "run_kern=booti ${loadaddr} ${rd_spec} ${fdtaddr}\0"
 
+#define EXTRA_ENV_J721E_BOARD_SETTINGS_UBI                             \
+       "init_ubi=run args_all args_ubi; sf probe; "                    \
+               "ubi part ospi.rootfs; ubifsmount ubi:flash_fs;\0"        \
+       "get_kern_ubi=ubifsload ${loadaddr} ${bootdir}/${name_kern}\0"  \
+       "get_fdt_ubi=ubifsload ${fdtaddr} ${bootdir}/${name_fdt}\0"     \
+       "args_ubi=setenv bootargs console=${console} ${optargs} "       \
+               "rootfstype=ubifs root=ubi0:flash_fs rw ubi.mtd=ospi.rootfs\0"
+
 /* U-Boot MMC-specific configuration */
 #define EXTRA_ENV_J721E_BOARD_SETTINGS_MMC                             \
        "boot=mmc\0"                                                    \
@@ -142,6 +150,7 @@
        DEFAULT_FIT_TI_ARGS                                             \
        EXTRA_ENV_J721E_BOARD_SETTINGS                                  \
        EXTRA_ENV_J721E_BOARD_SETTINGS_MMC                              \
+        EXTRA_ENV_J721E_BOARD_SETTINGS_UBI                              \
        EXTRA_ENV_RPROC_SETTINGS                                        \
        EXTRA_ENV_DFUARGS                                               \
        DEFAULT_UFS_TI_ARGS                                             \

After applying this, please rebuilt the u-boot and replace in the OSPI Flash. You can also add these environment variables at the u-boot prompt.

-4- Boot from file system in UBI partition of OSPI

Now you have the flashed tiny file system in the OSPI UBI, and also the modified u-boot with the environment to support it. Now change bootmode to OPSI and run the below:

=> run args_all
=> run args_ubi
=>
=> setenv boot ubi
=>
=>
# Here you can load from TFTP etc, you just need the DTB and kernel image in the RAM
# This is because we don't have Kernel image and DTB in the Tiny file system in UBIFS
=>
=> ext4load mmc 1:2 0x82000000 /boot/Image
16654344 bytes read in 337 ms (47.1 MiB/s)
=>
=> ext4load mmc 1:2 0x81200000 /boot/k3-j721e-common-proc-board.dtb
92333 bytes read in 5 ms (17.6 MiB/s)
=>
=> booti 0x82000000 - 0x81200000

NOTE: I've seen if you do a hard reboor (power OFF -> ON) when the UBIFS is mounted then the next time it corrupts the file system. Please use a soft reboor (run reboot at command from kernel) instead.

I can understand that the above instructions migh look a little overwhelming at first. Reason being that this out of the box is not supported / tested frequently. I can help you with more questions you have on the above process or in case you get stuck following the above.

Also, please let me know the whole use-case where the UBIFS file system will add value as then I can circle back to the team and look at the possibility of making this a part of the SDK.

Regards,

Karan