[Qemu-devel] Re: persistent tun & different virtual NICs & dead guest network

[Avi Kivity <avi@redhat.com>]

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Avi Kivity wrote:
>> I think all the settings should be reset to 0
>> when opening the tun device.
>
> This should definitely be fixed.  I'll look at writing a patch.
>

Okay, that's not in upstream qemu, so I committed a fix to 
kvm-userspace.git.

Attached if you want to test it.

-- 
error compiling committee.c: too many arguments to function


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>From 25971710409c374e9486c960c297f324a9164a65 Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@redhat.com>
Date: Sun, 5 Apr 2009 15:08:55 +0300
Subject: [PATCH] kvm: qemu: clear tap features on initialization

tap features change how tap interprets data, so they must be cleared on
initialization to prevent old settings from interfering with new guest
instances.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 qemu/net.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/qemu/net.c b/qemu/net.c
index d753fa0..703d01c 100644
--- a/qemu/net.c
+++ b/qemu/net.c
@@ -930,6 +930,7 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
 #endif
 #ifdef TUNSETOFFLOAD
     s->vc->set_offload = tap_set_offload;
+    tap_set_offload(s->vc, 0, 0, 0, 0);
 #endif
     qemu_set_fd_handler2(s->fd, tap_can_send, tap_send, NULL, s);
     snprintf(s->vc->info_str, sizeof(s->vc->info_str), "fd=%d", fd);
-- 
1.6.0.6