isa-variant

name	isa-variant
description	Add a new ISA variant (e.g., RV64I, RV32IMF) to the project. Covers updating the for_each_isa! table, dispatch macros, and IsaKind enums across remu_isa, remu_harness, remu_simulator_nzea, and remu_boot.

Files to modify (in order)

1. remu_isa/src/isa/extension_enum.rs — the table

Add a row to for_each_isa!:

$cb!(RV64I, u64, -, -, NoV, -, 0x80...0100, "rv64i", i, none, R);

Columns: Name, XLEN_type, has_M(+/-), has_F(+/-), VConfig_type, has_WJ(+/-), MISA_value, ISA_string, base_arch(i/im/ia/imac), ext_spec(none/wj/zve), platforms(R/N/RN)

The gen_isa_type! macro auto-generates the struct + RvIsa impl. No manual code needed.

Update gen_isa_type! 8 arms if the new ISA uses a new combination of +/- (e.g., adding an F-enabled variant when none existed before requires 4 new arms).

2. Platform IsaKind enums

For remu (remu_harness/src/isa_dispatch.rs):

• Add variant to RemuIsaKind enum
• Add match arm in from_isa_spec_or_panic

For nzea (remu_simulator_nzea/src/supported_isa.rs):

• Add variant to NzeaIsaKind enum (if nzea supports it)
• Add match arm in try_from_isa_spec

3. Dispatch macros (remu_boot/src/lib.rs)

Add match arms to dispatch_remu! and/or dispatch_nzea!:

RemuIsaKind::Rv64I => $runner.run_with_config::<$Config<RV64I>>($opt, $irq),

4. Import the new ISA type

In remu_boot/src/lib.rs, add to the use block:

use remu_isa::isa::extension_enum::{..., RV64I};

Platform support

When adding a new ISA, decide which platforms support it:

• RN in the table → both remu and nzea dispatch need arms
• R → only remu dispatch needs an arm
• N → only nzea dispatch needs an arm

Verification

cargo check --workspace --exclude remu_hal --exclude remu_app_hello_world --exclude remu_app_collection --exclude remu_app_mnist