刷tx2电脑遇到的apt-get install问题

ubuntu16.04，用来刷过tx2为3.3的系统。不管换国内国外各种源，总是提示以下问题，很纳闷，因为源里没有arm64的包。

Reading package lists... Done
E: Failed to fetch http://mirrors.tuna.tsinghua.edu.cn/ubuntu/dists/xenial/main/binary-arm64/Packages  404  Not Found [IP: 101.6.8.193 80]
E: Failed to fetch http://mirrors.tuna.tsinghua.edu.cn/ubuntu/dists/xenial-updates/main/binary-arm64/Packages  404  Not Found [IP: 101.6.8.193 80]
E: Failed to fetch http://mirrors.tuna.tsinghua.edu.cn/ubuntu/dists/xenial-backports/main/binary-arm64/Packages  404  Not Found [IP: 101.6.8.193 80]
E: Failed to fetch http://mirrors.tuna.tsinghua.edu.cn/ubuntu/dists/xenial-security/main/binary-arm64/Packages  404  Not Found [IP: 101.6.8.193 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.

但是一直没有出过问题，我也就没深究。

后来要在电脑上安装gstreamer，不管怎么换源，都会提示Package 'libgstreamer1.0-0' has no installation candidate

sudo apt-get install gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package gstreamer1.0-plugins-bad
E: Couldn't find any package by glob 'gstreamer1.0-plugins-bad'
E: Couldn't find any package by regex 'gstreamer1.0-plugins-bad'
E: Unable to locate package gstreamer1.0-plugins-ugly
E: Couldn't find any package by glob 'gstreamer1.0-plugins-ugly'
E: Couldn't find any package by regex 'gstreamer1.0-plugins-ugly'

sudo apt-get install libgstreamer1.0-0
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package libgstreamer1.0-0 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'libgstreamer1.0-0' has no installation candidate

排除掉源的问题，还更新了DNS，一直不起作用。

因为想用gstreamer在地面站显示机载电脑发回的视频，尽管可以不用，但一直耿耿于怀。

后来在这里看到https://askubuntu.com/questions/705895/how-to-fix-a-failed-to-fetch-binary-armhf-packages-error-during-apt-get-update

You might install the armhf cross tools which add armhf as foreign architecture (your architecture maybe i386 or amd64). You can launch this command to verify:

dpkg --print-foreign-architectures

If the output includes armhf, you can simply remove it by running the command:

sudo dpkg --remove-architecture armhf

源的更新只是提示，并没有说错误，更改后果然好了。

apt-get到arm64架构下搜索packages去了，应该是Jetpack给我装上的

dpkg --print-foreign-architectures
i386
arm64

apt-get remove .*:arm64
dpkg --remove-architecture arm64

然后sudo apt-get update就正常了