RE: missing info in the document for qemu networking (where to find linux-test-xxx.tar.gz) (TAP networking)

[ckim]

Hi, Peter Maydell and all,

> 
> Pretty sure that's just ancient out of date documentation. Anything that
> points to a random tar.gz file is probably years out of date.
> Jason, is there up to date information on setting up TAP somewhere?
> 
Thanks,

I found https://wiki.qemu.org/Documentation/Networking (it would be good to 
show this link in the main documentation's network part.)
And I tried that with this setup.

        sudo ip link add br0 type bridge
        sudo tuntap add dev tap0 mode tap
        sudo ip tuntap add dev tap0 mode tap
        sudo ip link set dev tap0 master br0
        sudo ip link set dev enp6s0 master br0
        sudo ip link set dev br0 up
        sudo ip address delete 129.254.31.181/24 dev enp6s0
        sudo ip address add 129.254.31.181/24 dev br0
        sudo ip route add default via 129.254.31.1 dev br0
        
        #sudo systemctl stop firewalld
        #-netdev tap,id=mynet0,ifname=tap0,script=no,downscript=no -device 
e1000,netdev=mynet0,mac=DE:AD:BE:EF:61:5C \
        
LD_LIBRARY_PATH=/usr/local/lib:/usr/local/lib::/usr/local/cuda/lib64:/usr/local/cuda/lib64:/home/ckim/prj/abdsn/ab21sim/axpusim/build
 &&
        ./qemu-system-aarch64 -nographic -machine 
ab21q,gic-version=max,iommu=smmuv3 -m 1G -cpu max -smp 4 \
        -netdev tap,id=vnet,ifname=tap0,script=no,downscript=no -device 
virtio-net-pci,netdev=vnet \
        -drive 
file=ab21q-ubuntu-20.04-image.img,if=none,id=drive0,cache=writeback -device 
virtio-blk,drive=drive0,bootindex=0 \
        -drive file=ubuntu-20.04-mini.iso,if=none,id=drive1,cache=writeback 
-device virtio-blk,drive=drive1,bootindex=1 \
        -drive file=flash0.img,format=raw,if=pflash -drive 
file=flash1.img,format=raw,if=pflash

Good thing is I can use network in the host as usual. After getting in to the 
VM, I did ( by the way I changed the guest machine IP to 129.254.31.183, same 
subnet)
        Sudo ifconfig enp0s1 129.254.31.183/24 up
        Sudo ip route add default via 129.254.31.1 dev enp0s1

I hoped I could use network in the VM, but I couldn't(can't ping or telnet to 
other machine, either way). 
This is the network config in the host and the guest. Just in case someone can 
check and point out what’s wrong.

  << in the host : 129.254.31.181 >> 
$ sudo ifconfig -a
br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 129.254.31.181  netmask 255.255.255.0  broadcast 0.0.0.0
        inet6 fe80::2efd:a1ff:fec7:1a61  prefixlen 64  scopeid 0x20<link>
        ether 2c:fd:a1:c7:1a:61  txqueuelen 1000  (Ethernet)
        RX packets 273494  bytes 105958971 (105.9 MB)
        RX errors 0  dropped 20862  overruns 0  frame 0
        TX packets 5823  bytes 4581307 (4.5 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp6s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 129.254.31.181  netmask 255.255.255.0  broadcast 129.254.31.255
        inet6 fe80::57bd:fa67:f336:73d7  prefixlen 64  scopeid 0x20<link>
        ether 2c:fd:a1:c7:1a:61  txqueuelen 1000  (Ethernet)
        RX packets 356078  bytes 142521235 (142.5 MB)
        RX errors 0  dropped 5450  overruns 0  frame 0
        TX packets 34994  bytes 39130194 (39.1 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device memory 0x90200000-9027ffff

enp7s0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 2c:fd:a1:c7:1a:60  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device memory 0x90100000-9017ffff

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 1776  bytes 210444 (210.4 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1776  bytes 210444 (210.4 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

tap0: flags=4098<BROADCAST,MULTICAST>  mtu 1500
        ether f2:00:3e:16:6e:62  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 307  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0


$ sudo brctl show
bridge name bridge id       STP enabled interfaces
br0     8000.2cfda1c71a61   no      enp6s0
                            tap0

  << in the guest : 129.254.31.183 >>
$sudo ifconfig -a
enp0s1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 129.254.31.183  netmask 255.255.255.0  broadcast 129.254.31.255
        ether 52:54:00:12:34:56  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 307  bytes 42358 (42.3 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 9939  bytes 711775 (711.7 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 9939  bytes 711775 (711.7 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0