镜像源：http://kernel.ubuntu.com/~kernel-ppa
镜像内容：Ubuntu内核包
添加原因：国内实在是太太太太太慢了

`# wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.13.9/linux-image-4.13.9-041309-lowlatency_4.13.9-041309.201710211231_amd64.deb
--2017-10-26 00:00:42-- http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.13.9/linux-image-4.13.9-041309-lowlatency_4.13.9-041309.201710211231_amd64.deb
Resolving kernel.ubuntu.com (kernel.ubuntu.com)... 91.189.94.216
Connecting to kernel.ubuntu.com (kernel.ubuntu.com)|91.189.94.216|:80... failed: Connection timed out.
Retrying.

--2017-10-26 00:02:51-- (try: 2) http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.13.9/linux-image-4.13.9-041309-lowlatency_4.13.9-041309.201710211231_amd64.deb
Connecting to kernel.ubuntu.com (kernel.ubuntu.com)|91.189.94.216|:80... failed: Connection timed out.
Retrying.

--2017-10-26 00:05:00-- (try: 3) http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.13.9/linux-image-4.13.9-041309-lowlatency_4.13.9-041309.201710211231_amd64.deb
Connecting to kernel.ubuntu.com (kernel.ubuntu.com)|91.189.94.216|:80... `