Author Topic: ZynqBerry kernel & rootfs trimming  (Read 1331 times)

NZ

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ZynqBerry kernel & rootfs trimming
« on: March 12, 2018, 12:25:50 PM »
Hello all. For work I have been experimenting with the ZynqBerry. Now me and the team would like to ditch the SD card and have all the software parts put into the flash memory on the board itself. I have this working with the 'test board' bare-bones reference design but the resulting image barely fits. It uses 15MB out of the available 16MB. That doesn't leave much room for our own bitstream and userland code.

So, I will have to start taking out drivers, modules and tools from the kernel and the rootfs to make room for our software. But, there's no information to be found on the wiki pages about the ZynqBerry's on-board devices and their corresponding driver modules. So before I start the trimming process I would like to have a list of these first so that I can safely skip the ones which are critical to the board's functioning.  ;)

TL;DR: Can anybody provide me with a list of the on-board devices of a ZynqBerry and their corresponding kernel modules?

JH

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Re: ZynqBerry kernel & rootfs trimming
« Reply #1 on: March 13, 2018, 09:57:32 AM »
Hello,
you found on board devices on our TRM:
Also manually changes additional needed to the default petalinux project:But there is no list available with optional kernel and rootfs settings, which are set automatically by the petalinux project generation.
Why do you use QSPI Flash for your user apps? You can use SD card for this. You can also use a partition of the SD Card for your Linux file system instead of RAM disk included into the image.ub
We have done this on our 2017.1 Debian Demo:br
John





NZ

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Re: ZynqBerry kernel & rootfs trimming
« Reply #2 on: March 13, 2018, 11:19:21 AM »
Ah well, I was hoping there'd be a list. I guess I'll just have to carefully hack away and make a number of trial-and-error attempts.

The main reason why I (and the team) want to put everything into the QSPI is to leave out another component that can fail. Especially when there's no securing clip to hold the SD card in place once the ZynqBerry is put into our sorting machines. These machines shake and vibrate so anything that relies on friction to be held in place is a liability. Perhaps we should've looked a bit harder for a Zynq equivalent with a larger QSPI or perhaps EMMC. But, hè, 640K is enough, right? :-D

Past experience from tinkering with previous boards and Linux kernels has taught me that I can get the kernel+rootfs down to <1.5MB and still have a functional board. So there's a lot of potential to reduce the 9 megs used by image.ub at the moment.

JH

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Re: ZynqBerry kernel & rootfs trimming
« Reply #3 on: March 13, 2018, 11:55:21 AM »
Hi,

there a lot of kernel and rootfs settings are enabled by default. Xilinx has enabled a little bit more than needed, so it's easier to start up and get an running system.
So you must try out. 

We provide also other Zynq modules with emmc on the module and greater QSPI Flash.  Maybe they are better suited for their purpose?

br
John