[libre-riscv-dev] evaluation of bit-witdh scoreboards

[Jacob Lifshay]

On Sat, Dec 15, 2018 at 3:51 AM lkcl <luke.leighton at gmail.com> wrote:

> we need to evaluate whether to drastically cut down the number
> of registers and use a 2k SRAM instead.
>
If the memory is shared between cores, it definitely won't be sufficient in
size and will be a total pain to implement since we will probably need to
have at least a port for each core.
It will work pretty well to have the 2k per-core sram treated by the
compiler as extra registers that can be only accessed by special move
instructions. Importantly, the SRAM will need to be not memory-mapped since
then we need to get the MMU involved and LLVM is designed to spill to the
stack rather than to a special memory region. Doing so allows us to shrink
the register file to 64 64-bit registers, shrinking it to 32 is cutting it
a bit close.

Jacob