FPGA Source / Project Repository

[shodruk]

That's great! Sorry, maybe I made a mistake. I'll try again.

[greytery]

[FHuettig]

[greytery]

My guess is that the 512MB is a left-over from the Zedboard time.

The 32MB of shared memory is at the top of the 1GB, but that leaves another 20+ MB unaccounted for.
I'm looking at increasing the amount of shared memory - I thought I understood the device tree mechanism. So the idea that the dts file already supported 512MB 'free' memory got me very excited there.

Note that shodruck's headless nano build @ also shows the same amount of memory.

tery

[tnt]

AFAIR the memory layout is given by u-boot to the kernel directly with the device tree node being ignored.

[greytery]

[greytery]

There seems to be an overlap between using the device tree and U-Boot, as far as defining how the board config information is fed to Linux.

Upstreaming U-Boot is being discussed at and there is 'pressure' on Adapteva to sign off and include Parallella U-Boot in the mainstream. Before that's done can we look at what should be in there??
What should be in the Device Tree and what should be in the U-Boot config?

A recompilation of the U-Boot is not something to be taken lightly because that involves the official U-Boot Git repositories and we could soon end up with different boot builds. (Looking at what the U-Boot files includes, it seems it's on the road to World Domination )
OTOH, Device tree configs are meant to be flexible, and the purpose is to avoid having multiple kernel or boot builds. Any changes are local to Parallella/Adapteva - or the developer/customer/me. The more that can be moved to the Device Tree the better!

Some board parameters are 'Hard' / fixed while others are more 'Soft', e.g. Total physical memory (1 GB) is 'Hard' but the amount that is made available to the OS (32MB) is 'Soft'. There may be other parameters - but that's the one I'm currently interested in. (So why is that 'memory' device ignored/not effective??)

This is relevant to FPGA Source reorganisation: the capability to reconfigure FPGA means that there may be other 'Hard' config parameters that may be impacted. So I really do believe it's worth having a good look at this - before the U-Boot upstreaming takes place.

tery

[tnt]

What other parameters are taken from u-boot beside the memory ? AFAIK it's the only one.

[greytery]

Back in the mists of time ....

It seems that the memory reservation was originally intended to be via the device tree, but it hit a snag. Seems a bug - or inconsistency - if the devicetree information is being ignored by bootm like this. Perhaps that's a penalty for using the universal boot loader. More RTFM'ing to do. Every day I'm jumping down yet another rabbit hole into Wonderland.

What other parameters ...? The parallella.h file defines various devices, such as ethernet. Maybe that's fine - I'm not knowledgeable enough. Nor do I know what the FPGA reprogramming is capable of. It just needs looking at by someone who actually knows what they're doing.

tery

[tnt]