The 850 KB/s dump measurement does not bound ROM streaming, and the tool could
not have measured streaming at all: it only counted TCP payload, so a
streaming capture would have reported ~zero throughput.
Swiss's ROM streaming runs in the game via the patch driver's own stack
(cube/patches/bba/tcpip.c), which contains no TCP whatsoever -- UDP + FSP,
plus ICMP and ARP. Reads are sized to the path MTU rather than 1024:
_fsp.data_length = MIN(length, env->pmtu - (fsp->data - eth->data));
so ~1446 B of payload per datagram at a 1500 MTU, with QUEUE_SIZE 2
outstanding and udp->checksum = 0x0000 (no payload checksum). None of the
menu path's TCP window, lwIP overhead or 1024-byte writes apply.
The analyser now counts UDP payload and picks the bulk direction by which way
the payload actually flows -- streaming is PC -> GC, the opposite of a disc
dump -- with --bulk to_gc to steer the gap analysis. Self-test H replays the
streaming shape (1446 B datagrams, 2 per request) and checks the bulk
direction is identified and the payload counted.
Recorded in the TODO that "can it stream?" is still OPEN, but open on the GC's
side: the dump established the adapter has headroom (zero retransmissions,
~17% W5100 bus utilisation, 26% of the EXI ceiling). The hard ceiling is
3375 KB/s and the GC's disc delivers ~2000-3100 KB/s, so full disc rate has no
margin -- but games read in bursts, not continuously at peak.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Roflin
4e7a2ef429