[meta-xilinx] mainline u-boot on zedboard

[Nathan Rossi]

On Wed, Jan 13, 2016 at 4:17 AM,  <gmane at reliableembeddedsystems.com> wrote:
> Hi,
>
> On 2016-01-11 02:08, Nathan Rossi wrote:
>>
>> uEnv.txt is something that is only in u-boot-xlnx. I do not believe it
>> will make an appearance as the default environment in mainline, this
>> is because the FIT format is much more complete and relies less on
>> magic environment configuration. In the future I was intending on
>> having meta-xilinx generate fit images (using wic) which would include
>> the main image components in a single binary and u-boot would just
>> load the default configuration.
>
>
> You mean that everything like kernel/fdt/fpga.bin/rootfs would be part of
> the fit image?

Yes, although not everything needs to be, aka if you are using a SD
rootfs the rootfs would not be part of the fit image. Or if you are
managing the fpga bitstream from kernel/userspace it likely would not
be in the fit image.

>
> How would you be able to support a setup where kernel/fdt/fpga.bin are
> loaded from tftp and the rootfs from nfs with a mainline u-boot then?

Assuming by rootfs from nfs your are referring to a NFS root (in which
the kernel handles mounting the NFS during boot). The kernel, dtb and
fpga bitstream would be stored in the fit image, since TFTP is not a
default boot mechanism U-Boot would need to be setup via environment
to load from TFTP (which at the moment would be setting
modeboot=jtagboot).

Alternatively there might be a way to take advantage of embedding
scripts into the fit image to handle custom boot sequences without
needing to change the environment.

Regards,
Nathan

>
> This is my (and most likely not only my) preferred development setup for all
> the boards I have lying around. Like this it's very easy to access my boards
> remotely and change everything (except for the boot loader) without needing
> manual intervention if I screw up things;)
>
>>
>> As for saveenv and general environment stored in flash support. The
>> QSPI driver was only added to mainline u-boot within the past few
>> months as such the surrounding setup still has to be completed.
>>
>> You will need to modify zynq-common.h to enable it.
>>
>> diff --git a/include/configs/zynq-common.h b/include/configs/zynq-common.h
>> index 0ab6083..a844062 100644
>> --- a/include/configs/zynq-common.h
>> +++ b/include/configs/zynq-common.h
>> @@ -199,6 +199,8 @@
>>  #ifndef CONFIG_ENV_IS_NOWHERE
>>  # ifndef CONFIG_SYS_NO_FLASH
>>  #  define CONFIG_ENV_IS_IN_FLASH
>> +# elif defined(CONFIG_ZYNQ_QSPI)
>> +#  define CONFIG_ENV_IS_IN_SPI_FLASH
>>  # elif defined(CONFIG_SYS_NO_FLASH)
>>  #  define CONFIG_ENV_IS_NOWHERE
>>  # endif
>>
>> This will use the QSPI flash if available for storing the environment.
>> After this saveenv/etc. will work. I quickly tested on a Zybo (I don't
>> have a Zedboard) and it works quite well albeit slowing the boot a bit
>> (~1 second or so).
>
>
> I would not mind about that.
>
> Unfortunately I am currently on the road and my Zedboard is not yet in my
> lab (where you or me could access it remotely). Hopefully next week I'll
> have some time and play with it.
>
> Regards,
>
> Robert
>