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WebXR: point to the public chromium-webxr-steam-frame repo

Browse Source 
The build script, launcher and Steam shortcut helper now live in
saphid/chromium-webxr-steam-frame, so drop the duplicate copies here.
The doc keeps the findings, verification and upstream status.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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saphidandClaude Opus 5.5 committed 2026-09-27 07:06:42 +10:00
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docs/webxr-chromium.md
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@@ -3,9 +3,11 @@
Goal: open a web VR180 or 360 player (DeoVR and DL8 embeds, WebXR samples),
press its VR button, and watch in 3D in the headset.
A standalone, public version of this build (build script, the SO_PEERCRED
patch, and a Frame-side installer that adds "Chromium XR" to the Steam library)
is at [saphid/chromium-webxr-steam-frame](https://github.com/saphid/chromium-webxr-steam-frame).
The build and installer now live in their own public repo,
[saphid/chromium-webxr-steam-frame](https://github.com/saphid/chromium-webxr-steam-frame):
a build script for an x86-64 Linux host, the SO_PEERCRED patch, and a
Frame-side installer that adds "Chromium XR" to the Steam library. This page
keeps the findings and what was verified on this Frame.
## Why Flathub Chromium can't
@@ -45,76 +47,53 @@ gets both.
SteamVR (`bin/linuxarm64/vrclient.so`, `VALVE_runtime_is_steamvr`). The
Linux backend uses Vulkan (`XR_USE_GRAPHICS_API_VULKAN`).
## Building it
## Building and installing it
[`scripts/build-chromium-xr.sh`](../scripts/build-chromium-xr.sh)
cross-compiles arm64 Linux Chromium on an x64 Linux host. It doesn't need
sudo: the arm64 sysroot comes from Chromium's own script. It needs about
90 GB of disk. It shallow-fetches the CL ref (patchset 44), runs
`gclient sync --no-history`, installs the sysroot, applies one extra seccomp
fix (below), builds `chrome` with `symbol_level=0` and proprietary codecs, and
packs `chromium-xr-arm64.tar.xz` (about 145 MB, GPU libraries included).
Progress is logged to `~/chromium-xr/stage`. The build aborts if the disk
holding `~/chromium-xr` drops below 12 GB free.
Follow the [public repo's README](https://github.com/saphid/chromium-webxr-steam-frame#build).
In short: `build/build.sh` on an x64 Linux host (no sudo, about 90 GB of
disk) produces `chromium-xr-arm64.tar.xz` (about 145 MB), and
`frame/install.sh` on the Frame unpacks it to `~/chromium-xr`, installs the
`chromium-xr` launcher in `~/.local/bin`, and adds the Steam library shortcut
through the Steam client's DevTools port, the same way as T3 Code
([apks.md](apks.md)). Launching the shortcut gives Chromium its own panel,
`valve.steam.desktopgame.<appid>`, like any other app.
First run, 2026-09-25, on a 12-core, 31 GB x64 Linux box: 9 h 33 min for
First build, 2026-09-25, on a 12-thread, 31 GB x64 Linux box: 9 h 33 min for
94,835 steps, giving Chromium 156.0.8071.0. A rebuild after a one-file change
takes under a minute, plus about 4 minutes to repack.
**The extra fix.** The CL's XR seccomp policy refuses `getsockopt`. SteamVR's
To debug from the Mac, start it with DevTools on the Frame:
`ssh frame 'DISPLAY=:0 ~/.local/bin/chromium-xr --remote-debugging-port=9223 URL'`, or
launch it as a panel with
`scripts/panel-on-frame.sh -- '~/.local/bin/chromium-xr' --remote-debugging-port=9223 URL`
([panels.md](panels.md)). DevTools has no authentication. It listens on
loopback, but with the userspace Tailscale from [tailscale.md](tailscale.md)
running, loopback ports are reachable from your tailnet. Close the browser
when you're done. Chromium runs one browser per profile, so close the
Steam-launched one first or the flag is ignored.
**The SO_PEERCRED fix.** The XR seccomp policy refuses `getsockopt`. SteamVR's
client calls `getsockopt(SOL_SOCKET, SO_PEERCRED)` inside `xrCreateInstance`,
so the XR process died with a seccomp crash (arm64 syscall 209). The script
allows that one option. That's needed but not enough: `launch` still turns
so the XR process died with a seccomp crash (arm64 syscall 209). The patch
allows that one option. It's needed but not enough: the launcher still turns
seccomp off (below), so the patch only matters once that's fixed too.
## Running it on the Frame
**Seccomp is off.** The launcher passes `--disable-seccomp-filter-sandbox`.
With the XR seccomp policy on, SteamVR's client reads `/proc/self/status`
through Chrome's file broker and gets the broker's pid. SteamVR then binds
the app to the wrong process ("Unable to init path manager:
VRInitError_Init_Internal") and `xrCreateInstance` fails. The broker can't
answer `/proc/self` for another process, so fixing this needs a change in
Chromium's broker client or in the CL. The namespace sandbox stays on, but
seccomp is off for every process, so use this profile for VR sites rather
than everyday browsing.
[`scripts/chromium-xr.sh`](../scripts/chromium-xr.sh):
```sh
BUILD_HOST=my-linux-box scripts/chromium-xr.sh install # your build host; scp, unpack to ~/chromium-xr
scripts/chromium-xr.sh launch [URL] # its own VR panel, --enable-features=OpenXR
scripts/chromium-xr.sh steam # adds "Chromium XR" to the Steam library
scripts/chromium-xr.sh check # prints isSessionSupported('immersive-vr')
```
It runs natively, not as a Flatpak. `launch` opens it as its own panel on
gamescope's X display, the same way as [`panel-on-frame.sh`](../scripts/panel-on-frame.sh) ([panels.md](panels.md)), so
the Plasma desktop doesn't need to be open. It uses its own profile
(`~/.config/chromium-xr`) and DevTools on loopback port 9223, so it doesn't
collide with the Flatpak's 9222. When a page enters VR, Chrome asks
**Allow VR?** in the browser panel; choose *Allow this time* or *Allow while
visiting the site*.
Both ways of starting it run
[`frame/chromium-xr/launch.sh`](../frame/chromium-xr/launch.sh), copied to
`~/Applications/ChromiumXR/launch.sh` on the Frame, which holds Chrome's flags.
It sits outside `~/chromium-xr` so `install` doesn't delete it.
**From the Steam library (verified 2026-09-26).** `steam` adds a non-Steam
shortcut called "Chromium XR" (with the Flathub Chromium icon, if that's
installed) through the Steam client's DevTools port, the same way as T3 Code
([apks.md](apks.md)), without restarting Steam. It saves the app id in
`~/Applications/ChromiumXR/shortcut-appid`, so rerunning it, even after you
rename the shortcut in the library, doesn't add a second one. On this Frame
the shortcut app id is 2240749789. Launching it from the library gives
Chromium its own panel, `valve.steam.desktopgame.2240749789`, like any other
app. A Steam launch doesn't open a DevTools port, so `check` needs `launch`.
Chromium runs one browser per profile: while the Steam-launched one is open,
`launch` opens its URL in that window, without DevTools, then prints
`failed: ... exited` because no new window appeared. Close it first.
**Seccomp is off.** The wrapper passes `--disable-seccomp-filter-sandbox`. With
the XR seccomp policy on, SteamVR's client reads `/proc/self/status` through
Chrome's file broker and gets the broker's pid. SteamVR then binds the app to
the wrong process ("Unable to init path manager: VRInitError_Init_Internal")
and `xrCreateInstance` fails. The broker can't answer `/proc/self` for another
process, so fixing this needs a change in Chromium's broker client or in the
CL. The namespace sandbox stays on, but seccomp is off for every process, so
use this profile for VR sites rather than everyday browsing. DevTools on
port 9223 has no authentication. It listens on loopback, but with the
userspace Tailscale from [tailscale.md](tailscale.md) running, loopback ports
are reachable from your tailnet. Close the browser when you're done.
**Upstream (2026-09-27).** CL 8441736 (the XR sandbox) has merged into
Chromium, still refusing `getsockopt`; CL 8132979 is still in review. Valve
and the CLs' author are working on Steam Frame support
([utzcoz/chromium-webxr-linux#5](https://github.com/utzcoz/chromium-webxr-linux/issues/5)).
Both sandbox problems above, with the patch, are reported in
[utzcoz/chromium-webxr-linux#7](https://github.com/utzcoz/chromium-webxr-linux/issues/7).
**Verified 2026-09-26** (Frame BUILD_ID 20260922.6101926, SteamVR 2.17.10,
this build):