Re: [libvirt] [PATCH 5/9] conf: new "managed" attribute for target dev of <interface type='ethernet'>

Although <interface type='ethernet'> has always been able to use an existing tap device, this is just a coincidence due to the fact that the same ioctl is used to create a new tap device or get a handle to an existing device. Even then, once we have the handle to the device, we still insist on doing extra setup to it (setting the MAC address and IFF_UP). That *might* be okay if libvirtd is running as a privileged process, but if libvirtd is running as an unprivileged user, those attempted modifications to the tap device will fail (yes, even if the tap is set to be owned by the user running libvirtd). We could avoid this if we knew that the device already existed, but as stated above, an existing device and new device are both accessed in the same manner, and anyway, we need to preserve existing behavior for those who are already using pre-existing devices with privileged libvirtd (and allowing/expecting libvirt to configure the pre-existing device). In order to cleanly support the idea of using a pre-existing and pre-configured tap device, this patch introduces a new optional attribute "managed" for the interface <target> element. This attribute is only valid for <interface type='ethernet'> (since all other interface types have mandatory config that doesn't apply in the case where we expect the tap device to be setup before we get it). The syntax would look something like this: <interface type='ethernet'> <target dev='mytap0' managed='no'/> ... </interface> This patch just adds managed to the grammar and parser for <target>, but has no functionality behind it. (NB: when managed='no' (the default when not specified is 'yes'), the target dev is always a name explicitly provided, so we don't auto-remove it from the config just because it starts with "vnet" (VIR_NET_GENERATED_TAP_PREFIX); this makes it possible to use the same pattern of names that libvirt itself uses when it automatically creates the tap devices.) Signed-off-by: Laine Stump <laine(a)redhat.com&gt; --- docs/formatdomain.html.in | 48 +++++++++++++---- docs/schemas/domaincommon.rng | 5 ++ src/conf/domain_conf.c | 51 +++++++++++++++---- src/conf/domain_conf.h | 1 + .../net-eth-unmanaged-tap.xml | 35 +++++++++++++ .../net-eth-unmanaged-tap.xml | 40 +++++++++++++++ tests/qemuxml2xmltest.c | 1 + 7 files changed, 160 insertions(+), 21 deletions(-) create mode 100644 tests/qemuxml2argvdata/net-eth-unmanaged-tap.xml create mode 100644 tests/qemuxml2xmloutdata/net-eth-unmanaged-tap.xml