fix: [ps2ip_rpc] explicit fixed-layout select_pkt across EE/IOP RPC

[fjtrujy]

Summary

select_pkt (the SIF-RPC payload that ee/rpc/tcpips sends to iop/tcpip/tcpips for select()) used struct fd_set and struct timeval directly in the wire layout. Both types have compiler-defined sizes that diverge between the EE and IOP compile environments, so the EE and IOP saw different field offsets in the same struct — a silent ABI mismatch.

The mismatch

Field	EE (newlib)	IOP (lwIP)
struct fd_set	~8 bytes (FD_SETSIZE=64, __fd_mask=ulong=8)	2 bytes (packed fd_bits[(MEMP_NUM_NETCONN+7)/8])
struct timeval	16 bytes (tv_sec/tv_usec 64-bit longs)	8 bytes (32-bit longs)

The two mismatches together meant every field of select_pkt after timeout lived at a different offset on each side. The EE wrote pkt->writeset_p / exceptset_p / writeset / exceptset at offsets the IOP never read; the IOP read garbage from the high half of the EE's tv_usec for what it thought were the writeset_p / exceptset_p pointers, ended up calling lwip_select with NULL fd-sets, and silently returned without modifying any bits.

This was harmless for ps2link (UDP only, never calls select), but broke mongoose-based servers on the IOP-side path (ps2_http): the listening socket was flagged as having an exception condition on the very first poll cycle (spurious eset bits), mongoose called mg_error("socket error"), and the listener was killed before the first client connection.

The fix

Lock the wire layout to a fixed shape that's identical on both compile units:

• Define ps2ip_rpc_fd_set as a fixed-size byte array unsigned char fd_bits[(MEMP_NUM_NETCONN + 7) / 8]. Size is driven by MEMP_NUM_NETCONN and matches lwIP's internal fd_set semantics.
• Replace struct timeval timeout in select_pkt with explicit s32 timeout_sec; s32 timeout_usec; fields. Each side reconstructs/decomposes its own native timeval at the boundary.

Net result: every field of select_pkt is at the same byte offset on EE and IOP, regardless of toolchain header definitions.

Files

• common/include/ps2ip_rpc.h — fixed-layout struct
• ee/rpc/tcpips/src/ps2ipc.c — EE side: convert local fd_set/timeval to wire shape
• iop/tcpip/tcpips/src/ps2ips.c — IOP side: convert wire shape to local fd_set/timeval

Test plan

• select_test_iop (in ps2_drivers) — listening-socket select probe shows rc=0 r=0 w=0 e=0 ticks (no spurious eset bits). Pre-fix: e=1 on the very first probe.
• mongoose ps2_http on the IOP-side path — sustains repeated HTTP bursts on real hardware without the listener being killed by mg_error("socket error").
• No regression in ps2link / ps2client (UDP) which don't exercise this path.

🤖 Generated with Claude Code

[uyjulian]

lgtm