----- "Anthony Liguori" <aligu...@us.ibm.com> wrote: > A lot of people copy libvirt's command line from ps -ef and then > wonder why the > VM isn't working correctly. Let's be kind and tell them what they > should do > instead. > > Without this patch, if you run with an invalid -net tap,fd=X, the > guest still > runs and we poll 100% on a bad file descriptor. With this patch, you > get: > > qemu: -net tap,fd=42: invalid fd= for tap network device. If you're > copying > from libvirt, use `virsh dom2xml-to-native' instead > qemu: -net tap,fd=42: Device 'tap' could not be initialized > > Signed-off-by: Anthony Liguori <aligu...@us.ibm.com> > --- > v1 -> v2 > - Remove garbage from unclean commit (spotted by Alex Graf) > > diff --git a/net/tap.c b/net/tap.c > index 0147dab..45b1fb6 100644 > --- a/net/tap.c > +++ b/net/tap.c > @@ -405,6 +405,8 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, > const char *name, VLANState *vlan > int fd, vnet_hdr = 0; > > if (qemu_opt_get(opts, "fd")) { > + int flags; > + > if (qemu_opt_get(opts, "ifname") || > qemu_opt_get(opts, "script") || > qemu_opt_get(opts, "downscript") || > @@ -418,6 +420,11 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, > const char *name, VLANState *vlan > return -1; > } > > + if (fcntl(fd, F_GETFL, &flags) == -1) { > + error_report("invalid fd= for tap network device. If > you're copying from libvirt, use `virsh dom2xml-to-native' instead"); > + return -1; > + } > +
Maybe we can use TUNGETFEATURES here to verify whether fd is a tap here? > fcntl(fd, F_SETFL, O_NONBLOCK); > > vnet_hdr = tap_probe_vnet_hdr(fd); > -- > 1.7.0.4