[meta-xilinx] u-boot/UBIFS

[Mike Looijmans]

(1) If you want to read (or write) data from ubifs partitions, then you need 
these config items indeed. If you just want an UBI rootfs, no u-boot support 
is required at all. In that case, you'll need to fetch the kernel from flash 
and boot it with the proper root= directives to point to the ubi partitions. 
To flash the device, boot it with e.g. an SD card and flash from within linux 
(ubiformat -f).

To set these environs, you'll probably need to patch u-boot. You could just 
define a new u-boot machine, you can look at the topic recipes on github which 
add new code for the miami boards based on zynq.

(2) There's an environment variable that points to a flash location for the 
environment. Just set up to where it is, and u-boot will use it.

(3) Probably not directly, though there's an emulation layer that may allow 
this. It's much easier to just tell Yocto to generate both an SD image (e.g. 
tar.gz) and a UBI image for the same rootfs.
(Note that the Xilinx images don't actually boot from SD card, they just copy 
and extract a root filesystem into RAM.)


On 19-09-15 02:39, Edward Wingate wrote:
> I'm trying to get UBIFS working on a custom Zynq 7020 board.
> I have the following issues:
>
> 1) I'm trying to build a u-boot.elf that has UBI support.
> I believe I need to re-compile u-boot with these config items:
> #define CONFIG_CMD_UBI
> #define CONFIG_CMD_UBIFS
> #define CONFIG_RBTREE
> #define CONFIG_MTD_DEVICE
> #define CONFIG_MTD_PARTITIONS
> #define CONFIG_CMD_MTDPARTS
> #define CONFIG_LZO
>
> Do I need a u-boot-xlnx_2015.04.bbappend file to specify these?  What
> would I put in it?
>
> 2) If I created a flash partition to store the u-boot environment, how
> do I go about creating an image that contains that environment? And
> how do I tell u-boot that this flash partition contains the
> environment for it (e.g., set another config item and re-compile
> u-boot)?
>
> 3) Can I use the Yocto-generated ubifs rootfs image on an SD card as
> well as on flash?  What u-boot configuration do I use to do this?  For
> example, for a ramdisk image, I'd put
> "ramdisk_image=rootfs.cpio.gz.u-boot" in uEnv.txt.  What would I need
> to use the ubifs image in place on the SD card?
>
> Thanks for your help.
>



Kind regards,

Mike Looijmans
System Expert

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