This release for the first time officially supports the riscv64 architecture, allowing users to run Debian on 64-bit RISC-V hardware and benefit from all Debian 13 features.
The Wiki provides more details about riscv64 support in Debian.
Downloads:
Risc-V has a base specification and then a bunch of extensions. RV64G is almost as basic as you can get. It has 64-bit registers as opposed to RV32s 32-bit ones and it has floating point instructions. C adds compressed instructions which are good for keeping more code in cache.
RVA23 is a “profile” which includes a lot more extensions. 56-bit virtual memory, vector processing, and hypervisor mode being the big ones. I don’t think anybody has come out with a RVA23 compliant piece of silicon yet.
So Debian is supporting existing hardware and Ubuntu has ditched support for the existing processors and is supporting what is currently yet to appear.
Thank you for the explanation!