su binary outdated

第一次试用cm的nightly颁布。su就用问题：
1, 打开su会提示su binary outdated.
2, 用ti备份恢复时，每个程序需要点10下左右才可以完成恢复。总算还可以将就。
为了能够在出游时可以用上自己的手机。我点了600多下，才把64个程序恢复完成，总算hold住了。

回家后，还是想把这个问题解决。试了一些方法都用来更新apk，都不成功。
最后，不知在哪里看到可以到su论坛（http://androidsu.com/superuser/）上下载signed.zip刷机。试一下果然有效。

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su binary是什么呢？

http://androidsu.com/superuser/
The app（superuser） consists of two parts, Superuser.apk and the su binary.

Superuser.apk runs as any other app and gives you, the user, a place to see what apps you have allowed or denied, as well as view a log of what apps have used su when.

The su binary is what other apps call when they need superuser rights. The binary checks the database maintained by Superuser.apk to determine if you have already granted rights to the requesting app, and if not tells Superuser.apk to display a prompt asking you for permission.