openstack 建立镜像时遇到 failed to find romfile "pxe-rtl8139.rom"

在ubuntu 12.04 中 建立openstack 镜像时会报如下信息：

sudo kvm -m 1024 -cdrom CentOS-6.2-x86_64-bin-DVD1.iso -drive   file=CentOS-6.2-x86_64.img,if=scsi,index=0 -boot d -net nic -net user -usbdevice tablet –nographic -vnc :4

kvm: pci_add_option_rom: failed to find romfile "pxe-rtl8139.rom"

只须要安装kvm-ipxe

apt-get install kvm-ipxe