TX2系统自带的官方源更新速度非常慢，但是比较稳定，官方源如下：
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://ports.ubuntu.com/ubuntu-ports/ xenial main restricted
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-updates main restricted
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-updates main restricted
## Uncomment the following two lines to add software from the 'universe'
## repository.
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
# deb http://ports.ubuntu.com/ubuntu-ports/ xenial universe
# deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial universe
# deb http://ports.ubuntu.com/ubuntu-ports/ xenial-updates universe
# deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-updates universe
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
# deb http://ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted
# deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted
deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security main restricted
deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-security main restricted
# deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security universe
# deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-security universe
# deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security multiverse
# deb-src http://ports.ubuntu.com/ubuntu-ports/ xenial-security multiverse
一般情况下我会将其更新为国内的中科大源：
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial-updates main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial-security main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial-security main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial-backports main restricted universe multiverse
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial main universe restricted
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ xenial main universe restricted
最近，在TX2上配置了各种环境，同时进行了相关的内存空间清理等工作，当我想在上面装tensorrt时，sudo apt-get update 居然各种报错，换源也报同样的错误，具体报错如下：
E: Failed to fetch http://mirrors.ustc.edu.cn/ubuntu-ports/dists/xenial-updates/main/binary-amd64/Packages 404 Not Found [IP: 202.141.176.110 80]
然后网上各种搜，换DNS、换网络、架构问题等，尝试均无效(目前仍未解决，后来刷机了)。
今天发现了源的问题，因为我执行了sudo dpkg --add-architecture amd64，，所以sudo apt-get update不成功，只要把它删除就可以了sudo dpkg --remove-architecture amd64
其实tx2刷机是有自带tensorrt的，但我想用5.0的版本，因此卸载了原来的版本，具体安装操作如下：
在官网下载tensorrt（需要帐号登录）：https://developer.nvidia.com/tensorrt
每个版本都有相应的安装说明，按照步骤进行即可。
这里推荐一个卸载软件包的方法：sudo aptitude remove xxx，可以将依赖一并卸载。