RDIMM flag on DDR5 devices

[biecho]

When building the bitstream for an RDIMM DDR5 device, I noticed that the generated litedram_settings.json file includes the following entry:

"is_rdimm": false

This seems to impact the training of the device. Is this behavior a bug? Should we manually set this value when using the build scripts?

[mtdudek]

Thanks for opening this issue.
I've checked Rowhammer code with its dependencies.
It turns out that this is_rdimm field is never used in the code base.
I'll remove this field from the litedram_settings.json.

As for training code in the third_party/litex/litex/soc/software/liblitedram/ddr5_training.c.
It does have an is_rdimm variable, but it's being set by read_module_type function, which reads DIMMs SPD memory to check for attached memory type.