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@Gaok1 Gaok1 released this 04 Apr 12:38
· 9 commits to main since this release
v1.26.0
5a7aefd

Raven v1.26.0

New Instructions — RV32A Extension

Full RV32A atomic instruction support:

  • LR.W / SC.W — load-reserved / store-conditional with per-hart reservation tracking
  • AMO variants: AMOSWAP, AMOADD, AMOXOR, AMOAND, AMOOR, AMOMAX, AMOMIN, AMOMAXU, AMOMINU
  • FENCE — now forwarded to the bus layer (was a no-op)
  • FENCE.I — invalidates the I-cache, enabling self-modifying code to work correctly

Instruction panel type badges extended: [A] for atomic, [F] for float.

Cache Coherence Bug Fixes

Four bugs that caused silent data corruption in multi-level cache (L1 D + L2) configurations, which could manifest as a program crash at PC=0x00000000:

  1. Blanket L2 invalidation after write-back stores removed — on a write-allocate miss, L2 was being invalidated right after the dirty eviction wrote back to it, losing data in both cache levels.
  2. Write-through stores now correctly invalidate L2 — stale L2 copies are now dropped after write-through stores so future misses re-read the updated value from RAM.
  3. sync_to_ram writeback order fixed — L2 (outer levels) is now flushed before D-cache to prevent stale L2 data from overwriting correct values in RAM.
  4. flush_all writeback order fixed — same root cause as #3; applied when the user toggles the cache off.

Pipeline Improvements

  • Per-FU stall counters — stall counts broken down by functional unit (ALU, MUL, DIV, FPU, LSU, SYS)
  • Configurable FU counts — set the number of each functional unit in .pcfg
  • Branch predictor expanded — not-taken (default), always-taken, BTFNT, and 2-bit dynamic strategies
  • Per-hazard stall breakdown in the pipeline footer
  • Speculative Gantt — in-flight speculative instructions shown with distinct styling; flushed instructions marked
  • .pcfg format updated: per-bypass-path flags replace the single forwarding boolean; fu.* count fields added

rust-to-raven

  • raven_api restructured: hart.rs moved to hardware_thread/
  • New atomic/ module: Arc, AtomicBool, AtomicU32, and friends backed by LR.W/SC.W — atomics actually work on the simulator now
  • main.rs updated to use the new HartTask closure-based API
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