Discussion (4 Comments)Read Original on HackerNews

rjsw•about 1 hour ago

The article doesn't mention anything about what FPGA image is loaded into the thing.

My guess would be that you can choose how to connect the CPU cores to the cache controller, you might want to run the CPUs independently.

throwa356262•about 1 hour ago

This is about the hard macros in Altera Cyclone V FPGA.

I suspect the issue is in how Altera configured the IP. They may simply have disabled some part to save on area.

rjsw•about 1 hour ago

In the equivalent AMD/Xilinx parts (Zynq), you connect up all the hard IP macros using the FPGA fabric.

throwa356262•about 1 hour ago

If the hard cores are configured with incorrect cache coherency options you may not be able to correct the issue in fpga fabric.

But this is pure speculation, I haven't checked Cyclone V documentation myself.

Why aren't my two Cortex-A9 cores cache coherent?