feat(libbboeos): Phase 4 — clang programs link against stub thunks#451
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Adds tools/generate_libbboeos_stubs.py that walks kernel/include/constants.asm for every FUNCTION_<NAME>_PTR entry without a matching FUNCTION_<NAME> legacy counterpart and emits a .S file with one 6-byte `jmp [absolute]` thunk per export. The Makefile compiles it to libbboeos_stubs.o, which is now linked before libbboeos.a in ports/doom/build.py and the test_libbboeos_qemu hello.c link. Because ld is single-pass left-to-right and only pulls archive members for unresolved symbols, the stubs satisfy every libbboeos export first, so the corresponding archive member (string.o + its bodies + rodata) is never pulled into the program. Bin/hello drops from 12,682 to 10,922 bytes; bin/doom drops from 659,942 to 658,182. Win scales as more libbboeos sources go behind the FUNCTION_<NAME>_PTR table. Also fixes the stale `[bboeos libc]` regex patterns in test_libbboeos_qemu.py (the marker was renamed to `[libbboeos]` in the libbboeos rename but the test wasn't updated since it's not in CI). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
tools/generate_libbboeos_stubs.py— walksFUNCTION_<NAME>_PTRentries inkernel/include/constants.asmand emits a one-jmp [absolute]-per-export.Sfile. Skips the legacy 13-entry block (those have bothFUNCTION_DIEandFUNCTION_DIE_PTRand aren't libbboeos C exports).libbboeos_stubs.o(default target nowall, which builds bothlibbboeos.aand the stubs).ports/doom/build.pyandtests/test_libbboeos_qemu.pylinklibbboeos_stubs.obeforelibbboeos.a. ld's archive pull rule (single-pass, satisfy-unresolved-only) means once the stubs define each libbboeos export, the correspondingstring.oarchive member is never pulled into the program.sizeof(string.o)per binary, and scales as more libbboeos C sources land behind the pointer table.[bboeos libc]regex patterns intest_libbboeos_qemu.py(marker was renamed to[libbboeos]in an earlier phase but the test wasn't updated since it's not in CI).Test plan
./make_os.shcleantests/test_asm.py(42/42)tests/test_programs.py(89/89)tests/test_bboefs.py(6/6)tests/test_archive.py(12/12)tests/test_kernel_archive.py(12/12)tests/test_cc_compatibility.py(57/57)python3 -m pytest tests/unit/(458/458)tests/test_libbboeos_qemu.py(manual; passes with stubs)python3 ports/doom/build.pysucceeds, binary 658,182 bytes🤖 Generated with Claude Code