C1 Report — Nova programs running natively in CosmoOS

Date: 2026-10-22. Status: C1 met on x86-64 and AArch64 (stage S0, out of tree). Script: integrations/cosmoos/c1.py (--corpus). Logs: out/cosmoos/c1-<arch>/ (not committed).

What ran

Item	Value
CosmoOS revision	30d34b29 (v1.0.9-11, branch b2-cosmofs-defects; its differences from main 4527d16d are cosmofs-only)
CosmoOS build	gmake ARCH=<arch> BUILD=release OUT=<Nova>/out/cosmoos/<arch>-release image (~4.5 min for x86-64)
Compiler	Apple clang 21.0.0 (CosmoOS's CC), ld.lld from the host toolchain (CosmoOS's LD)
novac	0.1.0-dev, commit 318f07d plus the C1 fixes in this change
Host	macOS on Apple silicon, QEMU TCG (qemu-system-x86_64 q35; qemu-system-aarch64 virt, cortex-a72)

The exact flags are recorded in out/cosmoos/c1-<arch>/flags.txt. They come from CosmoOS's Make (USER_CFLAGS, USER_LDFLAGS); none was copied by hand. For x86-64 they include -std=c11 -ffreestanding -nostdinc -fno-strict-aliasing -fno-pic -fno-pie -O2 -Werror -Wall -Wextra -Wshadow -Wvla -Wundef -Wpointer-arith -Wwrite-strings -Wstrict-prototypes -Wmissing-declarations -Wimplicit-fallthrough -Wcast-qual -Wformat=2 -Wdate-time. They link statically with -T userland/user.ld crt0.o … libc.a.

Results (both architectures)

Check	x86-64	AArch64
Generated C and the Nova runtime compile under the exact USER_CFLAGS (with -Werror)	pass (72 programs)	pass (72 programs)
Link against CosmoOS crt0.o + libc.a, with no undefined symbols and no compiler-rt needed	pass	pass: no outline-atomic helpers were required (an open question in the platform audit)
ELF: .note.cosmo (native personality), W^X PT_LOADs, non-executable PT_GNU_STACK	pass	pass
nova-hello prints NOVATEST: PASS, gcd(1071, 462) = 21, i64 min = -9223372036854775808	pass	pass
nova-panic prints its output, then nova panic: integer overflow at nova-panic.nova:5:23; the kernel logs exit status 134	pass	pass
Whole run corpus in the guest: 51 run-pass and 19 run-fail programs, with stdout, kernel-logged exit status and panic location matching the host expectations	70/70	70/70
CosmoOS shuts down cleanly (QEMU exit 33)	pass	pass
CosmoOS git status --porcelain unchanged	pass	pass

Serial excerpt (x86-64):

cosmo$ nova-hello
[ INFO] process: pid 17 'nova-hello' created, entry 0x0000000000400190, 3 segments
Hello from Nova on CosmoOS
gcd(1071, 462) = 21
i64 min = -9223372036854775808
NOVATEST: PASS
[ INFO] process: pid 17 'nova-hello' exited with status 0 (6 syscalls)
cosmo$ nova-panic
NOVAPANIC: before
nova panic: integer overflow at nova-panic.nova:5:23
abort()
[ INFO] process: pid 18 'nova-panic' exited with status 134 (57 syscalls)

The in-guest checker was mutation-tested against the real serial log: a wrong expected stdout, exit status or panic line are each reported.

How the image was made without touching CosmoOS

1. CosmoOS's own Make built the release image into Nova's out/ (OUT=).
2. The script read that boot archive (boot.tar, ustar) and rebuilt it with CosmoOS's scripts/mkbootarchive.py: all original entries in order, plus bin/nova-*.
3. It signed a new manifest with scripts/mkmanifest.py and the developer key (MODSIGN_KEY), and built the image with scripts/mkimage.sh.
4. It booted with scripts/qemu-run.sh (QEMU_ARCH selects the machine) and typed each program's name at the cosmo$ prompt, as CosmoOS's own shell harness does.

Problems found and fixed along the way

• llvm-readelf is not on this host's PATH, so the ELF checks now parse the headers in Python.
• qemu-run.sh selects the machine with QEMU_ARCH, not ARCH. The first AArch64 attempt booted the AArch64 image in x86 QEMU, and the script caught it (no prompt).
• novac must receive relative source paths, or host paths end up in panic messages.

What C1 does not show

• No CosmoOS CI job runs this. It is a local, manual run (stage S0). Moving it in-tree (stage S1: ports/nova-hello/ plus one rc.test line) needs the owner to choose it as a unit (OD-20).
• Only release images were booted. The debug image (with SELFTEST) was not tried.
• The programs use only write/exit/abort through libc stdio. No files, sockets or threads (C3).