[libvirt] [PATCH 0/3] A couple of UML-related fixes

[Soren Hansen]

I've been trying to get UML working for the last couple of days. As it stands,
at least bridged networking doesn't work for me.  I've got a fix, but I'm not
sure I'm doing it right.

I can get it to fail in three distinct ways:

 * With the current code, it seems that the tap device disappears almost
   immediately. This happens becuase the call to brAddTap includes an
   (int *)tapfd argument, so the tap device isn't persistent. A few
   lines after brAddTap, close(tapfd) is called and the tap device goes
   missing.

 * Passing a NULL tapfd argument to brAddTap and removing the call to
   close(tapfd) makes the tapfd persist, but when the uml domain
   attempts to bring up the interface, it fails with EBUSY. This turns
   out to be because brAddTap marks the tap device persistent, but
   doesn't close the fd, so both libvirt and uml have the fd open and
   that's doesn't work out well.

 * Finally, I tried passing the tapfd result back up the call chain so
   that I have a list of them that I could tell virExecDaemonize to keep
   open and then close them in libvirt after the fork. I think this is
   when I got EPERM when trying to bring the interface up in UML domain,
   but I'm not sure right now.

Also, I've had problems connecting to the domain's console.

These three patches seem to fix everything for me.

Soren Hansen (3):
  Close fd's of persistent tap devices
  Make umlConnectTapDevice ask brAddTap for a persistent tap device.
  Remove wrong check for uml monitor response size

 src/uml/uml_conf.c   |    6 +-----
 src/uml/uml_driver.c |    4 ----
 src/util/bridge.c    |    2 ++
 3 files changed, 3 insertions(+), 9 deletions(-)