[meta-xilinx] getting started for logicbricks ref designs

[Jean-Francois Dagenais]

> On May 30, 2016, at 09:07, Nathan Rossi <nathan at nathanrossi.com> wrote:
> 
> But the meta-xilinx
> layer does have the 'zybo-linux-bd-zynq7' machine which is a good
> example to work from.

Thanks, I had spotted it as a good example. Although I was a bit thrown off by
the "linux-bd" stuff in "recipes-bsp/reference-design/zybo-linux-bd.bb".

> 
> That is how it is implemented in meta-xilinx, although using
> EXTRA_IMAGEDEPENDS as that ensures the bitstream is output but not
> added to the root filesystem (although that depends on how/when you
> want to load your bitstream).

I guess I need the bitstream file to be loaded ASAP so I can get something on
the screen (splash). Perhaps by the first stage loader (as fpga.bin)? I think
the FSL is a "hacked" version of u-boot, is this still true?

> 
> I am not sure of the specifics on the Xylon drivers, you might need to
> check against resources provided by Xylon regarding what drivers are
> needed. Some of the documentation might be old and rely on older
> kernels (e.g. the current linux-xlnx master has xylon drm drivers
> instead of fbdev).
> 
> There is some in-kernel docs (linux-xlnx) on the logicvc and the xylon
> drm driver:
> ./Documentation/devicetree/bindings/drm/xylon/logicvc.txt
> ./Documentation/devicetree/bindings/drm/xylon/xylon_drm.txt
> 
> A bbappend is the right way, you can have .cfg/.scc fragment pairs
> added to the SRC_URI.

Xylon support team cues me I should remove the DRM driver in favour of their fb
driver found at:
https://github.com/logicbricks/driver_fb_logicvc/tree/master/kernel_src . I
guess I will just comply with this to start.

> 
> The linux-yocto bbappends in meta-xilinx are used to add kernel
> configuration to the linux-yocto kernels in order to use the
> linux-yocto kernels on Zynq/ZynqMP/MicroBlaze targets.
> 
> There are advantages and disadvantages to both kernels. Generally
> speaking, linux-yocto provides a better generic base kernel for most
> users as it provides support for Zynq hardware (due to mainline
> support for Zynq/ZynqMP/MicroBlaze), the linux-yocto kernel is also
> supported with continual updates, backports and mainline minor
> releases making it very useful for long term projects. But the driver
> support provided by linux-xlnx is required in a number of cases.

Yeah I'd like to benefit from that. But I assume I need all the configuration
stuff I get from linux-xlnx.inc. Would you say it's a bad idea to "git merge"
linux-yocto-4.4/standard/base into linux-xlnx/master but still use
linux-xlnx_4.4.bb? Both are 4.4. I guess I would not get all the kmeta and other
configuration fragments from linux-yocto though, am I correct?

Oh, sorry to all about my first post not respecting the usual 80 cols
netiquette! ;)


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