memory_libmap -lib : Found error in internal cell

[ben-j-c]

Version

Yosys 0.61 (git sha1 5ae48ee, g++ 13.3.0-6ubuntu2~24.04 -fPIC -O3)

On which OS did this happen?

Linux

Reproduction Steps

In yosys:

read_json sys_rtl.json
memory_libmap -lib memory_primitives.txt

sys_rtl.json

memory_primitives.txt

Expected Behavior

Error doesn't occur, mem_v2 are replaced with memory primitives.

Actual Behavior

ERROR: Found error in internal cell \sys.$flatten\fab.\char_d0.\d9.$auto$proc_rom.cc:155:do_switch$2246.0.30 ($basic_rom_32) at kernel/rtlil.cc:2664:

[ben-j-c]

I found a workaround or undocumented requirement. The name must start with $__ (double underscore) to have it do the mapping.

[KrystalDelusion]

May be worth mentioning on the memory docs as well, but it is documented on the techmap docs:

You can use the $__-prefix for internal cell types to avoid collisions with the user-namespace. But always use two underscores or the internal consistency checker will trigger on these cells.

https://yosyshq.readthedocs.io/projects/yosys/en/latest/yosys_internals/techmap.html#notes-on-using-techmap

Basically, cell types that start with $ or $_ are reserved for internal cells, so anything with that name will be treated as such and be subject to the internal error checker (which will fail on unrecognized cells).

[ben-j-c]

Thanks!

I also tried without the dollar sign (i.e., ram block basic_rom {<...>), but the parser seems to expect an id, not a string, so maybe thats unexpected.