git blame says:
d42700a3 (Stefan Majewsky 2015-08-22 14:05:17 +0200 270)
env.insert(QStringLiteral("HOME"), QStringLiteral("/"));
So, those lines have been there since A WHILE.
--
Russell
On Tue, Apr 22, 2025 at 4:51 PM Ben Koenig <[email protected]> wrote:
>
> Figured it out. SDDM has some code where they manually set the environment
> for their subprocesses which stomps on the system variables.
>
> So you are technically correct Russell, sddm forks off to a bunch of
> different subprocess. I checked the source code and sddm manually creates an
> environment for these processes to run in and sets that.
>
> <code>
> // create cursor setup process
> QProcess *setCursor = new QProcess();
> // create display setup script process
> QProcess *displayScript = new QProcess();
>
> // set process environment
> QProcessEnvironment env;
> env.insert(QStringLiteral("DISPLAY"), m_display);
> env.insert(QStringLiteral("HOME"), QStringLiteral("/"));
> env.insert(QStringLiteral("PATH"), mainConfig.Users.DefaultPath.get());
> env.insert(QStringLiteral("XAUTHORITY"), m_authPath);
> env.insert(QStringLiteral("SHELL"), QStringLiteral("/bin/sh"));
> env.insert(QStringLiteral("XCURSOR_THEME"),
> mainConfig.Theme.CursorTheme.get());
> setCursor->setProcessEnvironment(env);
> displayScript->setProcessEnvironment(env);
> </code>
>
> I patched it so HOME is set for "/root" and recompiled and BEHOLD - it
> stopped generating /.cache. Looks like upstream is not adhering to the system
> environment.
> -Ben
>
>
> On Tuesday, April 22nd, 2025 at 3:29 PM, Russell Senior
> <[email protected]> wrote:
>
> > The environment something runs in can sometimes be confusing. For
> > example, if the program forks, the exec operation that starts the
> > child can clear the environment. If you can start the program with an
> > strace wrapper, following forks and logging to a file, that might
> > shine some light on the problem. Something like:
> >
> > strace -f -ttt -s256 -o/tmp/strace-sddm.log <sddm-command-line>
> >
> >
> > where
> >
> > <sddm-command-line> is the normal startup command.
> >
> >
> > You'll have to figure out where that command is invoked.
> >
> > --
> > Russell
> >
> >
> > On Tue, Apr 22, 2025 at 3:21 PM Ben Koenig [email protected] wrote:
> >
> > > I'm sure that's what it is, but then that raises the question of WHICH
> > > variable. These are not undocumented features, and I've literally set all
> > > the relevant variables but it decides it doesn't care...
> > >
> > > sddm-greeter works as expected. It puts everything in /var/lib/sddm like
> > > a good little program.
> > >
> > > -Ben
> > >
> > > On Tuesday, April 22nd, 2025 at 3:13 PM, Russell Senior
> > > [email protected] wrote:
> > >
> > > > I didn't parse all the C code, but it could be something has an empty
> > > > variable ("") and that's getting appended with /.cache/<etc>
> > > >
> > > > --
> > > > Russell
> > > >
> > > > On Tue, Apr 22, 2025 at 3:10 PM Ben Koenig [email protected]
> > > > wrote:
> > > >
> > > > > I'll take a look at the QML_DISABLE_DISK_CACHE variable.
> > > > >
> > > > > I just did some testing and it looks like some part of SDDM or mesa
> > > > > is not obeying both the HOME and XDG_CACHE_HOME variables when sddm
> > > > > is launched. I confirmed that the vars are set in the environment
> > > > > when sddm.bin launches but it still creates 1.9MB of data in /.cache.
> > > > >
> > > > > -Ben
> > > > >
> > > > > On Tuesday, April 22nd, 2025 at 3:00 PM, Robert Detjens
> > > > > [email protected] wrote:
> > > > >
> > > > > > No disk cache in root on Fedora 42 / SDDM 0.21.0, though there are
> > > > > > some
> > > > > > under `/var/lib/sddm/`.
> > > > > > The systemd unit environment disables some other different disk
> > > > > > caching for
> > > > > > QT stuff, but the bug refs look unrelated to the shader cache:
> > > > > >
> > > > > > `# workaround https://bugzilla.redhat.com/1686675 # see also
> > > > > > https://bugreports.qt.io/browse/QTBUG-58508
> > > > > > QML_DISABLE_DISK_CACHE=1`
> > > > > >
> > > > > > On Tue, Apr 22, 2025 at 1:45 PM Ben Koenig [email protected]
> > > > > >
> > > > > > wrote:
> > > > > >
> > > > > > > Hey all, got a really random Linux question.
> > > > > > >
> > > > > > > Does anyone here who uses SDDM to log into their computer have a
> > > > > > > bunch of
> > > > > > > mesa cache files in /.cache ?
> > > > > > >
> > > > > > > Yes, that's a hidden .cache folder in /, you'll need to use 'ls
> > > > > > > -a /' to
> > > > > > > find it. I'm specifically interested in systems running sddm
> > > > > > > versions >=20
> > > > > > > but if you are on an older distro using 19 and have it that would
> > > > > > > be
> > > > > > > interesting as well...
> > > > > > >
> > > > > > > There's something funky going on in slackware -current and I'm
> > > > > > > too lazy to
> > > > > > > launch a new VM when I can ask users on other distros. That and
> > > > > > > the PLUG
> > > > > > > list has been a bit slow lately :)
> > > > > > >
> > > > > > > -Ben
