The session's proot runs with -i <app uid>, and the rootfs names that uid
root, so the client calls itself root while geteuid() returns the app's
uid. The read-only retry required geteuid() == 0 and never ran: the
Proton Experimental (ARM64) update still failed with Missing file
permissions on wineopenxr.dll (2026-09-26 16:07, 2,471 read-only files).
Also recognise the client by the path it was started by: the kernel's
/proc/self/exe names proot's loader for every process in the session.
The client runs as proot's root, which the kernel does not see, and
leaves many content files read-only; an update that rewrites one was
refused (EACCES) and cancelled with "Missing file permissions"
(Proton Experimental (ARM64), wineopenxr.dll). For the client's own
processes, a refused write-open of a file the app owns now gets the
owner's write bit - on the file, or on the directory a new file goes
into - and one more try. Games and Wine keep ordinary permissions.
From Bannerlator's feat/linux-gamescope-runtime since this repo was cut:
- Session teardown (4509d788): proot was SIGKILLed, which never lets its
--kill-on-exit cleanup run; its tracees lived on with no tracer, every
seccomp-trapped syscall failing with ENOSYS, spinning at a full core for over
an hour. Now SIGTERM, a grace for proot's own cleanup, SIGKILL only if it
will not go, then a sweep of the tree it had — snapshotted first, each pid
checked against its start time.
- The Steam client's controller interposer is its own source
(fakeinput_steam.cpp, 28922e7c), separate from the one preloaded into Wine.
- The seeder runs on a beat so a prefix the client creates mid-session is
covered before its install scripts run (6ee86bff).
- GE-Proton and proton-cachyos as compatibility tools: the registrar
bannerlator-proton-extra and the compat script's adopt_extras (03867656).
- space.c in the session shim: a library's own free space, not the phone's.
The env-vs-args ordering bug (98d38931) does not apply here: nothing is added
after the script name.
Lifts Bannerlator's Linux/gamescope runtime out into an app of its own: the
Wayland compositor, the proot session, the runtime installer, the fake-evdev
controller path and the PulseAudio server, with none of the Wine, container or
store machinery around them.
One activity installs the runtime from the same winlator-contents catalog and a
second one runs the session: compositor on a SurfaceView, gamescope and Valve's
native arm64 client under proot, a physical pad republished into the fake-input
rings, and the session's milestones on screen until the first frame arrives.
Kurt Himebauch