Electronics > FPGA

Microblaze 64 bit

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asmi:
Hey guys,

I've been recently checking out my new FPGA board which contains an SODIMM with 8 GBytes of DDR3, and naturally to get access to entire memory, I have to use 64 bit Microblaze. However I've noticed it to be utterly unstable:
1. Their "Memory Test" template from Vitis is simply broken (because they declare memory size as a u32 type, so obviously 8GB won't fit). It does passes once I fix it, however it only tests like first 1024 words, so a long way away from a true memory test. I did ended up modifying the application so it would actually perform a full memory test (which took AGES!), but I needed to confirm memory operation one way or another anyway.
2. None of lwip templates work, getting stuck at random locations of memory, and this location changes all the time, so I couldn't trace it to anything specific nor to find any logic in it.
3. Debugging is also a hit-and-miss, when stepping over some function in debugger CPU gets stuck somewhere, but if I place a breakpoint after that function and use "Run" command instead - it works just fine.

All those problems immediately go away if I use 32bit Microblaze (and of course I can only use 2GBytes DDR3 out of 8 GBytes due to address space limitations), so it doesn't seem that any of those problems are caused by anything board-related, which is the main thing I'm trying to establish at this moment.

With that I wonder, if anyone else has any experience with 64 bit MB to share - either good or bad, as I'm kind of at a loss at this point, not sure where to dig.

brucehoult:
Have you considered RISC-V? There are dozens of RISC-V cores, both 32 and 64 bit, which work fine in Xilinx FPGAs. You can find a lot of them (along with SoC framework to make them work) at...

https://github.com/enjoy-digital/litex

If you need professional support then there is at least (maybe others)...

https://info.bluespec.com/xilinx

asmi:

--- Quote from: brucehoult on September 28, 2023, 12:00:29 am ---Have you considered RISC-V? There are dozens of RISC-V cores, both 32 and 64 bit, which work fine in Xilinx FPGAs. You can find a lot of them (along with SoC framework to make them work) at...

https://github.com/enjoy-digital/litex

If you need professional support then there is at least (maybe others)...

https://info.bluespec.com/xilinx

--- End quote ---
I have my own RISC-V core, so I don't need someone else's ones, but that's not what this question is about. None of them can offer infrastructure that's even close to what you get from Xilinx for free.

brucehoult:
Very good.

Sad about the "utterly unstable" part, then.

asmi:

--- Quote from: brucehoult on September 28, 2023, 12:19:48 am ---Sad about the "utterly unstable" part, then.

--- End quote ---
This is what it seems for me, hence I want to hear about other people's experience with it, both good or bad as the case may be.

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