This is the mail archive of the systemtap@sourceware.org mailing list for the systemtap project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[Bug runtime/13078] investigate qemu virtio-serial channel for talking to stap-sh


https://sourceware.org/bugzilla/show_bug.cgi?id=13078

--- Comment #11 from Jonathan Lebon <jlebon at redhat dot com> ---
I created a udev rules file as well as a systemd template service file which
placed together in the VM spawns a stapsh instance for each detected port of
the type org.systemtap.[0-9]* (naming not formalized yet). Pretty sweet!

So all we would need to do is to make these files part of systemtap-runtime for
users to install in their VM (no added dependencies!) and on the host side have
stap-vm add the ports to the VM's definition to get the whole thing working.

For systems that do not have systemd, we can have a simple bash script which
looks for any of the org.systemtap.* ports and starts up one stapsh for each of
them (or exits if no ports are found). It would be helpful to make this script
long-lived, respawning any of the stapsh instances as they exit.

A minor issue is SELinux. It blocks qemu from creating sockets anywhere other
than in a directory with the qemu_var_run_t context. One good location
satisfying this is /var/lib/libvirt/qemu (recommended by dberrange in
BZ598533#c6).

The last major hurdle left is permissions. We have no issues on the guest side
since systemd/init spawns stapsh. However, on the host side, the UNIX socket is
created with qemu:qemu 755. There are no options to change this. These
permissions come from a umask(022) call in libvirtd, which qemu then inherits.
I'll have to contact the libvirt guys to see if they have any ideas.

-- 
You are receiving this mail because:
You are the assignee for the bug.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]