老的命令：
/root/BUILD_qemu/bin/qemu-system-x86_64 -enable-kvm -m 2G -cpu Nehalem -smp cores=4,threads=2,sockets=2 -numa node,mem=1G,cpus=0-8,nodeid=0 -numa node,mem=1G,cpus=9-15,nodeid=1 -display vnc=0.0.0.0:1 -net nic,vlan=1,model=virtio,macaddr='00:00:00:01:00:01' -net tap,vlan=1,ifname=tap-int,script=no,downscript=no -device virtio-net-pci,netdev=dev1,macaddr='00:00:00:01:00:02',vectors=32,mq=on -netdev tap,ifname=tap-0,id=dev1,script=no,downscript=no,vhost=on,queues=16 -drive file=disk.img,if=virtio -cdrom /root/CentOS-7-x86_64-DVD-1511.iso -boot order=c
在qemu-2.11-0 会报错如下：
qemu-system-x86_64: -net nic,vlan=1,model=virtio,macaddr=00:00:00:01:00:01: 'vlan' is deprecated. Please use 'netdev' instead.
详细用法：https://qemu.weilnetz.de/doc/qemu-doc.html#Network-options
摘要：
-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn] This option is a shortcut for configuring both the on-board (default) guest NIC hardware and the host network backend in one go.
The host backend options are the same as with the corresponding -netdev options below. The guest NIC model can be set with model=modelname.
Use model=help to list the available device types. The hardware MAC address can be set with mac=macaddr. The following two example do exactly the same, to show how -nic can be used to shorten the command line length (note that the e1000 is
the default on i386, so the model=e1000 parameter could even be omitted here, too): qemu-system-i386 -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32 qemu-system-i386 -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
简单解释：
两个方法：
A，用 -netdev和-device配合，-device需要志明model和mac，已经netdev的名字（这里是n1）是两个配置连接起来。
所有可选的参数见：
[root@D128 j]# /root/BUILD_qemu/bin/qemu-system-x86_64 -device help
不同的设备参数不同，需要查询详细的选项，如e1000e
[root@D128 j]# /root/BUILD_qemu/bin/qemu-system-x86_64 -device e1000e,help e1000e.rombar=uint32 e1000e.disable_vnet_hdr=uint8 (Do not use virtio headers, perform SW offloads emulation instead) e1000e.x-pcie-lnksta-dllla=bool (on/off) e1000e.bootindex=int32 e1000e.multifunction=bool (on/off) e1000e.romfile=str e1000e.vlan=int32 (Integer VLAN id to connect to) e1000e.command_serr_enable=bool (on/off) e1000e.x-pcie-extcap-init=bool (on/off) e1000e.addr=int32 (Slot and optional function number, example: 06.0 or 06) e1000e.mac=str (Ethernet 6-byte MAC Address, example: 52:54:00:12:34:56) e1000e.netdev=str (ID of a netdev to use as a backend) e1000e.subsys_ven=uint16 (PCI device Subsystem Vendor ID) e1000e.subsys=uint16 (PCI device Subsystem ID)
B， 使用简化的命令，-nic，功能同A。同样需要指明model和mac。可选参数见：
[root@D128 j]# /root/BUILD_qemu/bin/qemu-system-x86_64 -nic model=help qemu: Supported NIC models: e1000,e1000-82544gc,e1000-82545em,e1000e,i82550,i82551,i82557a,i82557b,i82557c,i82558a,i82558b,i82559a,i82559b,i82559c,
i82559er,i82562,i82801,ne2k_pci,pcnet,rocker,rtl8139,virtio-net-pci,vmxnet3 [root@D128 j]#
改过之后的启动脚本：
/root/BUILD_qemu/bin/qemu-system-x86_64 -enable-kvm -m 2G -cpu Nehalem -smp cores=4,threads=2,sockets=2 -numa node,mem=1G,cpus=0-8,nodeid=0 -numa node,mem=1G,cpus=9-15,nodeid=1 -display vnc=0.0.0.0:1 -device e1000e,netdev=dev0,mac='00:00:00:01:00:01' -netdev tap,ifname=tap-int,id=dev0,script=no,downscript=no,vhost=on -device virtio-net-pci,netdev=dev1,mac='00:00:00:01:00:02',vectors=32,mq=on -netdev tap,ifname=tap-0,id=dev1,script=no,downscript=no,vhost=on,queues=16 -drive file=disk.img,if=virtio -cdrom /root/CentOS-7-x86_64-DVD-1511.iso -boot order=c &
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依照如下步骤。虽然能编译，也能用，但是用起来还是有问题的，不清楚为什么。
比如： 1. kvm不好用，运行起来特别慢。2。 旧的image无法boot。
----------------- update ---------------
改了些编译参数，再编译：
[root@D128 qemu-2.12.0-rc3]# yum install ncurses-devel
[root@D128 qemu-2.12.0-rc3]# ./configure --enable-curses --enable-vhost-user --prefix=/root/BUILD_qemu/ --target-list=x86_64-softmmu --disable-gtk --enable-docs --enable-numa --enable-kvm --enable-modules --enable-system --enable-linux-user
支持了什么，configure的输出里都会打印出来。
可能会造成影响的参数包括
--enable-modules --enable-system --enable-linux-user
以上的参数，对效果影响没有区别。。。。
跟其他同事又找了一组设置：
./configure --disable-bluez --disable-brlapi --disable-curses --disable-debug-tcg --disable-fdt --disable-guest-agent --disable-live-block-migration --disable-qom-cast-debug --disable-sdl --disable-sparse --disable-strip --disable-vnc-jpeg --disable-xen --enable-docs --enable-kvm --enable-lzo --enable-seccomp --enable-snappy --enable-werror --block-drv-ro-whitelist=vmdk,vhdx,vpc,https --block-drv-rw-whitelist=qcow2,raw,file,host_device,nbd,gluster,blkdebug,luks --disable-xen-pci-passthrough --disable-guest-agent-msi --enable-attr --enable-coroutine-pool --enable-debug-info --enable-gnutls --enable-numa --enable-system --enable-tools --enable-vhost-net --enable-vhost-vsock --enable-vnc --enable-debug --tls-priority=NORMAL --with-coroutine=ucontext --extra-cflags="-O2 -g -pipe -Wall -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIE -DPIE" --extra-ldflags=" -pie -Wl,-z,relro -Wl,-z,now" --target-list=x86_64-softmmu
还是不行。。。
再试一次：卸载掉qemu-2.0.0的rpm，安装自编译的qemu到系统目录。
[root@D128 qemu-2.12.0-rc3]# yum autoremove qemu qemu-kvm
[root@D128 qemu-2.12.0-rc3]# ./configure --enable-curses --enable-vhost-user --target-list=x86_64-softmmu --disable-gtk --enable-docs --enable-numa --enable-kvm --enable-system --enable-modules
还是不行。。。 算了。。。
始终提示CPU STUCK
回退一个版本到2.10
[root@D128 qemu]# git branch master * stable-2.10 [root@D128 qemu]# git submodule init Submodule 'roms/QemuMacDrivers' (git://git.qemu.org/QemuMacDrivers.git) registered for path 'roms/QemuMacDrivers' [root@D128 qemu]# git submodule update --recursive
再编译：
还是不行。。。。
错误类似：
[ 28.050008] BUG: soft lockup - CPU#2 stuck for 23s! [systemd-udevd:162] [ 56.050010] BUG: soft lockup - CPU#2 stuck for 23s! [systemd-udevd:162] [ 84.050006] BUG: soft lockup - CPU#2 stuck for 23s! [systemd-udevd:162] [ 112.050007] BUG: soft lockup - CPU#2 stuck for 22s! [systemd-udevd:162] [ 140.050006] BUG: soft lockup - CPU#2 stuck for 22s! [systemd-udevd:162] [ 168.050009] BUG: soft lockup - CPU#2 stuck for 22s! [systemd-udevd:162] [ 196.050008] BUG: soft lockup - CPU#2 stuck for 22s! [systemd-udevd:162] [ 224.050006] BUG: soft lockup - CPU#2 stuck for 22s! [systemd-udevd:162] [ 252.050014] BUG: soft lockup - CPU#2 stuck for 22s! [systemd-udevd:162] [ 280.050006] BUG: soft lockup - CPU#2 stuck for 22s! [systemd-udevd:162]
退到2.9版本：
2.9也是这样。好的，放弃了。。。。
========================== 我又回来了，@ 2018-04-20 =====================
一直耿耿于怀这个问题。
那么，首先，soft lookup到底是什么问题？ 见：
https://www.cnblogs.com/lyhabc/p/6640012.html
简单的说，就是内核出了问题。然后我用的是标准CentOS7的发行版，所以基本上就是驱动的问题。
那么对于一个qemu的虚拟机来说，唯一能做的就是改变硬件，如下：
我去掉了所有的网卡，并且去掉disk的virtio驱动。
果然正常运行了！
/root/BUILD_qemu/bin/qemu-system-x86_64 -enable-kvm -m 2G -cpu Nehalem -smp cores=4,threads=2,sockets=2 -numa node,mem=1G,cpus=0-8,nodeid=0 -numa node,mem=1G,cpus=9-15,nodeid=1 -display vnc=0.0.0.0:1 -drive file=disk.img
查看文档，改变一下参数，重新把virtio用起来。
在那之前，再编一个qemu-2.12
[root@D128 qemu-2.12.0-rc3]# ./configure --prefix=/root/BUILD_qemu/ --target-list=x86_64-softmmu --disable-gtk --enable-virtfs
不认识virtio，换了参数也不行：
# -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=disk0,bootindex=1 # -drive file=disk.img,if=none,id=disk0
kvm+virtio 就会有问题。很可能是VMware的原因。
--------------------------
差一个题外内容：
What is the difference and relationship between “xx-softmmu” and “xx-linux-user”? To put it simply, xxx-softmmu will compile qemu-system-xxx, which is an emulated machine for xxx architecture (System Emulation).
When it resets, the starting point will be the reset vector of that architecture. While xxx-linux-user, compiles qemu-xxx,
which allows you to run user application in xxx architecture (User-mode Emulation). Which will seek the user applications'
main function, and start execution from there. See https://en.wikipedia.org/wiki/QEMU#Operating_modes
https://stackoverflow.com/questions/32435138/what-is-the-difference-and-relationship-between-xx-softmmu-and-xx-linux-user?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa