On Mon, Oct 03, 2016 at 02:59:02PM +0100, Stefan Hajnoczi wrote: > On Wed, Sep 28, 2016 at 02:08:15PM +0100, Daniel P. Berrange wrote: > > If the ftrace backend is compiled into QEMU, any attempt > > to start QEMU while non-root will fail due to the > > inability to open /sys/kernel/debug/tracing/trace_on. > > s/trace_on/tracing_on/ > > > > > Add a fallback into the code so that it connects up the > > trace_marker_fd variable to /dev/null when setting > > EACCESS on the 'trace_on' file. This allows QEMU to > > run, with ftrace turned into a no-op. > > I wonder whether a warning is appropriate. It depends on the situation > because maybe QEMU was compiled with multiple backends and we don't care > about ftrace when it fails to initialize...
If a distro compiles ftrace in, then I don't think we want to be spamming stderr with a warning every time the user runs QEMU as non-root. We could warn only if we failed to open it while running as root, but that'd basically be a no-op unless someone has broken their root account terribly. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|
