cosim-gpu: Skill for Claude Code

Cosim vHost

Interact with the cosim vHost Linux through a successful test session kept alive with just test-gpu --keep-alive <program>. A just run-launch session keeps the console attached to the terminal instead of creating a detached console pipe.

Prerequisites

The launcher or test runner prints the active console log and control pipe:

Console log: /path/to/qemu.log
Console pipe: /tmp/<session-name>-<run-id>.session/console.in

If those lines are unavailable, derive the paths from the run id and session name:

SESSION_NAME=qemu-cosim-tests
RUN_ID=<run-id>
CONSOLE_PIPE="/tmp/${SESSION_NAME}-${RUN_ID}.session/console.in"
CONSOLE_LOG="/tmp/${SESSION_NAME}-${RUN_ID}.log"
docker ps --filter name=gem5-cosim --format '{{.Names}}: {{.Status}}'
test -p "$CONSOLE_PIPE"
test -f "$CONSOLE_LOG"

Sending Commands

printf '%s\n' '<command>' > "$CONSOLE_PIPE"
printf '\003' > "$CONSOLE_PIPE"   # Ctrl-C
tail -n 80 "$CONSOLE_LOG"

Wait pattern:

baseline=$(wc -l < "$CONSOLE_LOG")
printf '%s\n' '<command>' > "$CONSOLE_PIPE"
while true; do
    current=$(wc -l < "$CONSOLE_LOG")
    if [[ "$current" -gt "$((baseline + 3))" ]]; then
        tail -20 "$CONSOLE_LOG"
        break
    fi
    sleep 2
done

Common operations

Mount 9p share

printf '%s\n' 'mount -t 9p -o trans=virtio,version=9p2000.L cosim_share /mnt' > "$CONSOLE_PIPE"

After mounting, paths under /mnt must resolve inside the shared tree. Host symlinks that point outside the shared repository will appear in the vHost but may resolve to an unmounted vHost path. If a script or artifact is missing through such a symlink, classify it as a vHost bridge path issue and rerun with a vHost-visible path before using the result as model evidence.

Do not assume any particular Host storage layout for artifacts. One developer may keep artifacts as a real directory, another may point it at a larger disk, and a CI worker may use a temporary workspace. Runner scripts that execute in the vHost should therefore use a configurable vHost-visible bridge path inside the shared tree, while final logs, matrices, verdicts, and provenance are still archived under the requested artifact directory. The transient bridge directory is not evidence by itself; preserve its script and output under the row artifact before cleanup.