Roflin
147ef8fcfc
Compat TODO item 2, the last silent-corruption risk. RXFrameAssembler took the RX ring as a compile-time constant (pages 1-15), so a driver configuring a SMALLER ring was ignored and we kept writing pages it would never read, with nothing reporting an error. The bounds now come from bp/rhbp, wired in BBATop from the GC's BP (0x0A/0B) and RHBP (0x1A/1B) registers, and both the page wrap and the free-space calculation use them. Garbage is rejected rather than obeyed: the driver's values are used only when bp >= 1 (page 0 is the TX buffer), rhbp <= 0x0F and rhbp > bp. Otherwise the hardcoded layout stands and geom_honoured goes low, so a mismatch is observable. Without that check BP=0 or an RHBP below BP gives a zero or negative ring size and the assembler writes outside it. ⚠️ Recorded as a known limitation: a ring must be LARGER than _MAX_FRAME_PAGES (6) or nothing is ever stored, because a frame's length is unknown until EOF so the worst case (1518+4 = 6 pages) is reserved up front. Found the honest way -- the test was written with RHBP=4 first and passed VACUOUSLY, storing nothing at all. Making that work needs a length-aware reservation, which is a bigger change than this one. T7 (8-page ring honoured, frames only in pages 1-8, and at least one actually stored) and T7b (all three garbage cases rejected, fallback still stores). Mutation-tested: wrapping at the hardcoded page 15 writes pages 9-11 and fails T7; removing the sanity check fails all four T7b assertions. Item 1 (RX filtering) remains the only open gap. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>