alpha-crtl: 3 rungs so REAL zlib 1.3.1 links zero-deferred out-of-box

src/vmslink/mk_decc_shr.sh

@@ -246,7 +246,27 @@ if [ "$OVMX_DECC_ARCH" = alpha ]; then
     #     (x86_64/aarch64) DECC$SHR.
     #   ovmx_get_libc -- OVMX loader glue (ovmx_libc_stub.c), likewise a
     #     plain OVMX-original name never decorated.
-    VEC="$VEC,__init_libc=PROCEDURE,__copy_tls=PROCEDURE,__init_tp=PROCEDURE,ovmx_get_libc=PROCEDURE"
+    #   ___errno_location -- the port's errno ACCESSOR. musl's <errno.h> defines
+    #     `errno` as `(*__errno_location())` (a plain, undecorated C name), so
+    #     EVERY consumer TU that touches errno emits a reference to it. It is
+    #     "musl-internal", NOT a recognized DEC C RTL surface name, so the alpha
+    #     cc1 does NOT decorate it to decc$* and the ^decc$ enumeration above
+    #     misses it -- exactly as it misses __init_tp/__copy_tls. (The DEC-C-
+    #     decorated decc$get_errno_addr IS exported via the bootstrap surface
+    #     above, but that is DEC C's own errno ABI, not the accessor musl-
+    #     compiled consumer code references.)
+    #       NAME FORM: the C symbol is `__errno_location` (two leading
+    #     underscores; that is how GNU nm reports it in libc.a). LINK.EXE's EVAX
+    #     symbol reader represents an external C symbol with ONE leading
+    #     underscore prepended, uniformly for the musl DEFINITION and for every
+    #     consumer REFERENCE -- so at the link/vector level the name is
+    #     `___errno_location` (THREE underscores). A real port consumer that uses
+    #     errno (gzread.c in zlib, and most real C) references `___errno_location`
+    #     and fails %LINK-F-UNDEF without this export; the two-underscore C form
+    #     does NOT match it. Defined in musl-alpha libc.a
+    #     (src/errno/__errno_location.c), resolved by the strict whole-archive
+    #     link below.
+    VEC="$VEC,__init_libc=PROCEDURE,__copy_tls=PROCEDURE,__init_tp=PROCEDURE,ovmx_get_libc=PROCEDURE,___errno_location=PROCEDURE"
 
     # stdin/stdout/stderr -- the C stdio stream FILE* objects, plain DATA names
     # the decc$ filter above cannot catch. The alpha cc1 does NOT decorate the

tools/cross-alpha-vms/joint-e2e/build-joint-image.sh

@@ -135,9 +135,19 @@ echo "-- compiling joint_main.obj (cross cc1, -mpointer-size=64) --"
 "$ALPHA_CC" -mpointer-size=64 -g0 -c /joint/joint_main.c -o "$OUT/joint_main.obj"
 
 # ---- 6. the JOINT-E2E IMAGE: real crt0 + real main, --use the genuine
-#         alpha DECC$SHR, STRICT (no --allow-undefined; expect zero deferred) ----
-echo "== linking joint-e2e image (strict, expect zero deferred) =="
-"$WORK/LINK.EXE" --transfer __main --use "$WORK/DECC\$SHR.EXE" \
+#         alpha DECC$SHR *and* LIBOTS$SHR, STRICT (no --allow-undefined;
+#         expect zero deferred) ----
+# LIBOTS$SHR.EXE is added to the canonical consumer link recipe alongside
+# DECC$SHR.EXE (zlib-crtl-rungs). The alpha-dec-vms port compiler lowers every
+# integer divide/remainder to an OTS$DIV_*/OTS$REM_* call (Alpha has no integer-
+# divide instruction), and those universals live in the SEPARATE LIBOTS$
+# shareable -- DECC$SHR imports OTS$ for its OWN use but does NOT transitively
+# re-export it, so a consumer that divides (zlib, and most real C) would defer
+# OTS$DIV_UL/OTS$REM_UI against DECC$SHR alone. LINK binds only REFERENCED
+# imports, so adding --use LIBOTS$ is inert for programs (like this joint_main)
+# that emit no OTS$ call, and closes the gap for those that do.
+"$WORK/LINK.EXE" --transfer __main \
+    --use "$WORK/DECC\$SHR.EXE" --use "$WORK/libots/LIBOTS_SHR.EXE" \
     -o "$OUT/joint_e2e.exe" "$OUT/crt0.obj" "$OUT/joint_main.obj"
 
 cp "$WORK/LINK.EXE" "$WORK/DECC\$SHR.EXE" "$WORK/libots/LIBOTS_SHR.EXE" "$OUT/"

tools/cross-alpha-vms/musl-arch/arch/alpha-dec-vms/unixio.h

@@ -0,0 +1,59 @@
+/*
+ * unixio.h -- DEC C UNIX-I/O emulation declarations for the OVMX
+ * alpha-dec-vms musl port CRTL include surface (bead: zlib-crtl-rungs).
+ *
+ * WHAT THIS IS.  On a genuine OpenVMS DEC C toolchain, <unixio.h> is the
+ * CRTL header that declares the UNIX-style low-level I/O emulation entry
+ * points (open/close/read/write/lseek/... on RMS underneath).  Portable C
+ * that targets VMS routinely does `#ifdef VMS #include <unixio.h>` (zlib's
+ * zconf.h is the canonical example) because on VMS these decls do NOT come
+ * from <unistd.h>.  The alpha-dec-vms GCC port predefines VMS/__VMS, so that
+ * `#ifdef VMS` fires -- correctly, it IS a VMS toolchain -- and the compile
+ * then needs <unixio.h> on the include path.
+ *
+ * WHY IT LIVES HERE.  The OVMX alpha-dec-vms port's C run-time is musl
+ * (whole-archived into DECC$SHR.EXE).  musl already IMPLEMENTS every one of
+ * these UNIX-I/O entry points -- this header only DECLARES them (no bodies),
+ * so it is a faithful, minimal shim: it makes the VMS-only header name
+ * resolvable without adding or faking any functionality.  It is scoped to the
+ * alpha-dec-vms arch overlay (a VMS-target-only header, exactly as on a real
+ * DEC C kit), never surfaced for a non-VMS target.
+ *
+ * Signatures track musl's own <unistd.h>/<fcntl.h> declarations exactly, so a
+ * translation unit that includes BOTH <unixio.h> and <unistd.h> sees identical
+ * prototypes (no conflicting-declaration diagnostic).  Types come from
+ * <sys/types.h> (size_t/ssize_t/off_t/mode_t), same as the real header.
+ *
+ * CLEAN-ROOM (Rule 8): declarations derived from the public DEC C RTL
+ * Reference Manual's <unixio.h> surface + musl's own prototypes.  No VSI/HPE
+ * header source was read or copied.
+ */
+#ifndef _OVMX_UNIXIO_H
+#define _OVMX_UNIXIO_H
+
+#include <sys/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int     open(const char *, int, ...);
+int     close(int);
+ssize_t read(int, void *, size_t);
+ssize_t write(int, const void *, size_t);
+off_t   lseek(int, off_t, int);
+int     dup(int);
+int     dup2(int, int);
+int     isatty(int);
+int     unlink(const char *);
+int     access(const char *, int);
+int     ftruncate(int, off_t);
+int     fsync(int);
+int     chdir(const char *);
+char   *getcwd(char *, size_t);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _OVMX_UNIXIO_H */