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Re-laned P -> A by the coordinator, 2026-08-30. The guess came from the test SOURCE (.pas -> Track P). The failing job is test-asm — the x86-64 assembler / disassembly emitter — which is Track A whatever language it is fed. test_asm_emit_x64 reports undefined variable (EmitSyscall) in compiler/x64enc.inc, and the only code commit touching that file in the range is 3a0ed43fb (--rtl-libc converts the mnemonic-emitted syscalls). Nothing here is Pascal-frontend work.

Master is NOT broken. Measured at HEAD by the coordinator: make compiler/pascal26 exits 0, converged after 2 round(s), fixedpoint a3f0f9e3325f. So this red is specific to the test-asm path, not a general build break — do not read it as one.

Track guessed as P from the test source. The ranker reads frontmatter, so this line — not the body — decides who works it; correct it if the guess is wrong.

origin/master has advanced 2 commit(s) since this sha. Re-verify at current HEAD before acting — the callback is tagged to the sha that was tested, which may no longer be the state of the tree.

regression: test-asm#src:test/hello.pas red at 97c5fba007f9 (auto-filed by twatch)

Repro

tools/testmgr.py --tier native --job 'test-asm#src:test/hello.pas' at 97c5fba007f96db42b4f4a5698512b66355632df

Range

The named sha 97c5fba007f9 CANNOT be the cause — it touches no buildable file (docs / tickets / tstate only). It is the sha that was TESTED, i.e. the upper bound of an untested range; the cause is somewhere below it.

bad 97c5fba007f9, last good 31198d3674df, 2 commit(s) in range — the watcher narrows this by idle bisect; check tstate/TSTATE.md for the current range.

Log tail

ok: /tmp/testmgr-scratch-619868/test_asm_dis_hello26.s  [-S disassembly]
ok: /tmp/testmgr-scratch-619868/test_asm_dis_hello26  [code=65360B  data=2760B  bss=42452B  procs=129]

Stub ticket: signal only. Track T agent (face 2) enriches or a dev track takes it from the repro line.

TRIAGED 2026-08-30 (frankA) — NOT the EmitSyscall defect; bisected to 75d2ba662

Filed in the same batch as regression-test-asm-test-asm-emit-x64 and regression-test-asm-test-x64enc, which WERE caused by 3a0ed43fb (x64enc.inc gaining an EmitSyscall reference) and are fixed in 658f4bea5. This one is a different commit. Do not close it on that fix.

Bisected, two builds one commit apart, nothing else changed:

build test_asmcore_x64
75d2ba662^ (= eb340e59d) all asmcore_x64 checks passed, exit 0
75d2ba662 (page-separate code from data) SIGSEGV, exit 139

The asmcore case is an out-of-bounds write, not a failed assertion

Symbolised at test_asmcore_x64.pas:191, after that line's output appeared — so it is temporary cleanup, not the statement itself:

lea    0x451fb8,%rax
mov    %rax,%rdi
xor    %rax,%rax
movabs $0xf0,%rcx        { 240 }
rep stos %al,(%rdi)      { SIGSEGV }

240 bytes zeroed from 0x451fb8. The single PT_LOAD ends at 0x451fc4 (vaddr 0x400000 + memsz 0x51fc4), so only 12 of the 240 bytes are mapped. filesz puts data ending at 0x43b35c, so the object is in BSS and is the LAST object in it: a BSS allocation ~228 bytes shorter than its own zero-init, at the one place in the image where nothing absorbs the overrun.

Two candidate causes ruled out by measurement rather than argument:

The hello/compiler cases are the padding reaching the disassembler

test-asm runs -S and asserts ! grep -q "^ db ". The padding zeros disassemble as runs of add [rax], al with one odd byte over: exactly one db 00, line 14704 of 14704 — the last line. The assertion is working; the padding really is undisassemblable bytes inside the code segment.

That is a design call, not a bug: either the padding moves out of the disassembled range, or the assertion exempts a trailing pad. 75d2ba662's own argument that the padding is safe ("zero is udf #0 on aarch64 and faults on x86-64") is about a stray jump and is not in tension with this — disassembly simply was not considered.

Owner: compiler/elfwriter.inc is b4's file. Diagnosis only from here; no edit made.

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