[fjtrujy]

Problem

The previous exception packet allocates sizeof(exception_frame_t) + 8 + 128 bytes, but writes an extra four-byte packet header before the frame. A 124-127-character IOP module name can therefore overrun the static buffer by up to four bytes during exception handling.

Fix

• Replace offset arithmetic with a fixed-layout, 16-byte-aligned C packet structure, including command header, frame, relative EPC, name length and 128-byte name field.
• Copy at most 127 module-name characters and always write the terminating NUL inside that field.
• Preserve existing EE-side wire offsets (name at word 43) and RPC command format.
• Add a portable C regression test for layout, short/empty/long names and boundary truncation; run it in GitHub Actions and block releases if it fails.

Validation

• Native C layout/boundary test: passed.
• Local PS2 SDK IOP + EE cross-build: passed (make -j4 LOADHIGH=0).
• git diff --check: passed.
• Real PS2 deliberate IOP exception tests remain recommended before merging.