Re: [oe-core][PATCHv9 0/6] Display manager proposal for x11 and wayland

[Randolph Sapp <rs@ti.com>]

On Thu Sep 18, 2025 at 6:03 PM CDT, Joshua Watt wrote:
> On Thu, Sep 18, 2025 at 4:42 PM Randolph Sapp <rs@ti.com> wrote:
>>
>> On Thu Sep 18, 2025 at 5:39 PM CDT, Randolph Sapp via lists.openembedded.org wrote:
>> > On Thu Sep 18, 2025 at 5:35 PM CDT, Joshua Watt wrote:
>> >> On Thu, Sep 18, 2025 at 4:31 PM Randolph Sapp <rs@ti.com> wrote:
>> >>>
>> >>> On Thu Sep 18, 2025 at 5:25 PM CDT, Joshua Watt wrote:
>> >>> > On Thu, Sep 18, 2025 at 3:49 PM Randolph Sapp via
>> >>> > lists.openembedded.org <rs=ti.com@lists.openembedded.org> wrote:
>> >>> >>
>> >>> >> From: Randolph Sapp <rs@ti.com>
>> >>> >>
>> >>> >> We've recently run into some issues with weston-init attempting to start Weston
>> >>> >> prior to all drm devices being registered. There's not really a good, scriptable
>> >>> >> mechanism to listen in to device registration events that works with the
>> >>> >> existing weston-init package. Well, at least one that doesn't involve polling
>> >>> >> files or introducing more dependency on the init system being used.
>> >>> >
>> >>> > It's not clear how switching to emptty actually solves that problem; I
>> >>> > don't see anything in my (brief) look at the emptty code that would
>> >>> > lead me to believe it actually cares about any drm devices being
>> >>> > present or handles devices showing up dynamically. Can you maybe
>> >>> > elaborate more on this?
>> >>>
>> >>> It doesn't currently have any tests to wait for the DRM device. I still need to
>> >>> look into adding that, but what it currently does is add a retry event counter
>> >>> and a small delay between retries that is better than the current console
>> >>> implementations. Especially considering authentication is handled separately
>> >>> from this retry process.
>> >>>
>> >>> By centralizing display manager specific code, common checks and fallback logic
>> >>> can be more easily implemented in the future. I'm hoping this lays the
>> >>> groundwork to let me address some other issues I've seen in multi-card
>> >>> environments as well.
>> >>
>> >> For the systemd parts, is it also possible to solve this with e.g.
>> >>
>> >> Requires=dev-dri-card0.device
>> >> After=dev-dri-card0.device
>> >>
>> >> (or similar) ? Seems like anything emptty would be doing would be a
>> >> reimplementation of the logic that already exists in systemd to do
>> >> that.
>> >
>> > It gets messy. A udev rule needs to be made to make systemd track that device.
>
> Ya, that's pretty normal.

Udev is dependent on systemd. Eudev exists, but why would we pull that in simply
to manage displays. It's not necessary for anything else at the moment.

>> > In a multi-card environment a device without an actual display may be picked.
>> > Systemd cannot directly solve the issue on it's own.
>
> Sure, but isn't that what udev is for? I don't think adding selection
> of a drm device makes sense in emptty. Regardless of init system, it
> really feels like selection of the correct device to use for display
> should be a udev problem.

Udev can track events but it does not report existing states. If a display is
already plugged in during boot then we won't know. We can catch the plug event
and operate on it, but otherwise it's a guess to see what we can do at boot.

For quite some time there has been a service to *manage displays* prior to
starting the desktop environment. GDM is a good example of that. Greetd is
another. Lightdm is another. Emptty is just an example of a useful all-rounder
with a permissive license I thought people would appreciate.

>> Additionally, there are more init systems supported here than just systemd...
>>
>> >>> >> I also see there is also a lot of scripting around starting X11,
>> >>> >> xserver-nodm-init, that (from my limited review) should experience the same
>> >>> >> issue.
>> >>> >>
>> >>> >> I'd like to introduce the following display manager for oe-core, emptty [1].
>> >>> >> This display manager is, as described upstream, a "Dead simple CLI Display
>> >>> >> Manager on TTY". It supports both x11 and wayland sessions, with togglable build
>> >>> >> parameters to completely remove x11 and pam dependencies. It's licensed MIT,
>> >>> >> which shouldn't be an issue for any users. (It is written in Go, if you have
>> >>> >> opinions about that.)
>> >>> >>
>> >>> >> With this, both weston-init and the xserver-nodm-init packages can be re-tuned
>> >>> >> to leverage this display manager and simply add a user and emptty config for an
>> >>> >> autologin session. This can resolve the current behavior across init systems
>> >>> >> without additional scripting, and move some development out of this layer.
>> >>> >>
>> >>> >> This lists myself as a maintainer of emptty as well as xserver-nodm-init and
>> >>> >> xuser-account since these are currently unassigned and I've reworked them
>> >>> >> significantly here.
>> >>> >>
>> >>> >> Sorry for the delay on this series. I found a few bugs in emptty that I wanted
>> >>> >> to address before submitting this officially.
>> >>> >>
>> >>> >> [1] https://github.com/tvrzna/emptty
>> >>> >>
>> >>> >> v2:
>> >>> >>         - Address spelling issues in commit messages
>> >>> >>         - Attempt to resolve some test related issues with weston
>> >>> >>         - Add additional logs to X11 related tests
>> >>> >> v3:
>> >>> >>         - Reset AUTOLOGIN_MAX_RETRY to the default value of 2. When running
>> >>> >>           under QEMU the first auth attempt almost always fails.
>> >>> >> v4:
>> >>> >>         - Add a tmpfile entry for the x11 domain socket directory.
>> >>> >>         - Remove some scripts associated with weston-init that were being
>> >>> >>           shipped with weston
>> >>> >> v5:
>> >>> >>         - Move tmpfile data to individual files
>> >>> >>         - Add explicit entries for these in the FILES variable
>> >>> >> v6:
>> >>> >>         - Do not attempt to ship a tmpfiles.d entry in libx11
>> >>> >> v7:
>> >>> >>         - Include a backported fix for go/runtime to address segfault issues
>> >>> >>           reported on x86 platforms in previous revisions
>> >>> >> v8:
>> >>> >>         - Sign-off backported patch
>> >>> >> v9:
>> >>> >>         - Resolve merge conflict in maintainers file
>> >>> >>
>> >>> >> Randolph Sapp (6):
>> >>> >>   libx11: create tmpfile dir for x11 domain socket
>> >>> >>   go: fix sigaction usage on i386 platforms
>> >>> >>   emptty: add version 0.14.0
>> >>> >>   weston-init: convert to virtual-emptty-conf
>> >>> >>   weston: remove deprecated weston-start scripts
>> >>> >>   xserver-nodm-init: convert to virtual-emptty-conf
>> >>> >>
>> >>> >>  .../conf/distro/include/default-providers.inc |   1 +
>> >>> >>  meta/conf/distro/include/maintainers.inc      |   6 +-
>> >>> >>  meta/lib/oeqa/runtime/cases/weston.py         |  18 +-
>> >>> >>  meta/lib/oeqa/runtime/cases/xorg.py           |   8 +
>> >>> >>  meta/recipes-devtools/go/go-1.25.0.inc        |   1 +
>> >>> >>  ...ng-cgo-on-386-call-C-sigaction-funct.patch | 248 ++++++++++++
>> >>> >>  meta/recipes-graphics/emptty/emptty-conf.bb   |  14 +
>> >>> >>  meta/recipes-graphics/emptty/emptty.inc       |  26 ++
>> >>> >>  .../recipes-graphics/emptty/emptty/emptty.tab |   1 +
>> >>> >>  meta/recipes-graphics/emptty/emptty/pamconf   |  10 +
>> >>> >>  meta/recipes-graphics/emptty/emptty_0.14.0.bb |  53 +++
>> >>> >>  meta/recipes-graphics/wayland/weston-init.bb  |  61 +--
>> >>> >>  .../wayland/weston-init/emptty.conf           |  77 ++++
>> >>> >>  .../recipes-graphics/wayland/weston-init/init |  54 ---
>> >>> >>  .../wayland/weston-init/weston-autologin      |  11 -
>> >>> >>  .../wayland/weston-init/weston-socket.sh      |  20 -
>> >>> >>  .../wayland/weston-init/weston-start          |  76 ----
>> >>> >>  .../wayland/weston-init/weston.env            |   0
>> >>> >>  .../wayland/weston-init/weston.service        |  71 ----
>> >>> >>  .../wayland/weston-init/weston.socket         |  14 -
>> >>> >>  .../weston/systemd-notify.weston-start        |   9 -
>> >>> >>  .../wayland/weston/xwayland.weston-start      |   6 -
>> >>> >>  .../recipes-graphics/wayland/weston_14.0.2.bb |  10 -
>> >>> >>  .../x11-common/xserver-nodm-init/X11/Xsession |  38 --
>> >>> >>  .../X11/Xsession.d/13xdgbasedirs.sh           |  19 -
>> >>> >>  .../X11/Xsession.d/89xdgautostart.sh          |   7 -
>> >>> >>  .../X11/Xsession.d/90XWindowManager.sh        |   7 -
>> >>> >>  .../x11-common/xserver-nodm-init/Xserver      |  25 --
>> >>> >>  .../xserver-nodm-init/capability.conf         |   2 -
>> >>> >>  .../xserver-nodm-init/default.desktop         |   5 +
>> >>> >>  .../xserver-nodm-init/emptty.conf.in          |  77 ++++
>> >>> >>  .../xserver-nodm-init/gplv2-license.patch     | 355 ------------------
>> >>> >>  .../x11-common/xserver-nodm-init/xserver-nodm |  75 ----
>> >>> >>  .../xserver-nodm-init/xserver-nodm.conf.in    |   7 -
>> >>> >>  .../xserver-nodm-init/xserver-nodm.service.in |  11 -
>> >>> >>  .../x11-common/xserver-nodm-init_3.0.bb       |  57 +--
>> >>> >>  meta/recipes-graphics/xorg-lib/libx11/99_x11  |   1 +
>> >>> >>  .../xorg-lib/libx11_1.8.12.bb                 |  15 +-
>> >>> >>  .../user-creation/xuser-account_0.1.bb        |   3 +-
>> >>> >>  39 files changed, 581 insertions(+), 918 deletions(-)
>> >>> >>  create mode 100644 meta/recipes-devtools/go/go/0001-runtime-when-using-cgo-on-386-call-C-sigaction-funct.patch
>> >>> >>  create mode 100644 meta/recipes-graphics/emptty/emptty-conf.bb
>> >>> >>  create mode 100644 meta/recipes-graphics/emptty/emptty.inc
>> >>> >>  create mode 100644 meta/recipes-graphics/emptty/emptty/emptty.tab
>> >>> >>  create mode 100644 meta/recipes-graphics/emptty/emptty/pamconf
>> >>> >>  create mode 100644 meta/recipes-graphics/emptty/emptty_0.14.0.bb
>> >>> >>  create mode 100644 meta/recipes-graphics/wayland/weston-init/emptty.conf
>> >>> >>  delete mode 100644 meta/recipes-graphics/wayland/weston-init/init
>> >>> >>  delete mode 100644 meta/recipes-graphics/wayland/weston-init/weston-autologin
>> >>> >>  delete mode 100755 meta/recipes-graphics/wayland/weston-init/weston-socket.sh
>> >>> >>  delete mode 100755 meta/recipes-graphics/wayland/weston-init/weston-start
>> >>> >>  delete mode 100644 meta/recipes-graphics/wayland/weston-init/weston.env
>> >>> >>  delete mode 100644 meta/recipes-graphics/wayland/weston-init/weston.service
>> >>> >>  delete mode 100644 meta/recipes-graphics/wayland/weston-init/weston.socket
>> >>> >>  delete mode 100644 meta/recipes-graphics/wayland/weston/systemd-notify.weston-start
>> >>> >>  delete mode 100644 meta/recipes-graphics/wayland/weston/xwayland.weston-start
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/X11/Xsession
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/X11/Xsession.d/13xdgbasedirs.sh
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/X11/Xsession.d/89xdgautostart.sh
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/X11/Xsession.d/90XWindowManager.sh
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/Xserver
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/capability.conf
>> >>> >>  create mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/default.desktop
>> >>> >>  create mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/emptty.conf.in
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/gplv2-license.patch
>> >>> >>  delete mode 100755 meta/recipes-graphics/x11-common/xserver-nodm-init/xserver-nodm
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/xserver-nodm.conf.in
>> >>> >>  delete mode 100644 meta/recipes-graphics/x11-common/xserver-nodm-init/xserver-nodm.service.in
>> >>> >>  create mode 100644 meta/recipes-graphics/xorg-lib/libx11/99_x11
>> >>> >>
>> >>> >> --
>> >>> >> 2.51.0
>> >>> >>
>> >>> >>
>> >>> >>
>> >>> >>
>> >>>
>>