guest_system_load_exec_standard_error compared the host standard error of
the re-executed child with "started <mode>\n" exactly. On a Linux kernel
without asynchronous userfaultfd write protection (before 6.7, such as
WSL2's 6.6) libc prints "[memory] write watch unavailable: ..." to the
host standard error at start-up, so the comparison failed and the test
aborted on every run. That one diagnostic line is now skipped when it
comes first; the rest of the host stream must still be the child's line
exactly, and the guest pipe must still be empty.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01En5cnt6RwCiNXDJwm9t8Tf
The re-executed image is told apart by an environment variable. With an argument list (fexecve) it sees argc 1 and the marker as argv[0]; with a null list (execv) it sees only its path.
A forked child with stderr on a pipe moves the guest's descriptor 2 to a
second pipe with dup2, then starts itself again through
sceSystemServiceLoadExec("/app0/eboot.bin"). What the new image writes
to stderr must reach the first pipe and nothing the second. It fails
with the previous execv, where the text goes to the guest's pipe.
