出现如下问题：
1.repo init时报错：

......
object 30d452905f166b316152f236422f85c8aa75a2d0
type commit
tag v1.7.5
tagger Shawn O. Pearce <sop@google.com> 1307663540 -0700

repo 1.7.5

gpg: Signature made Fri 10 Jun 2011 07:52:20 AM CST using DSA key ID 920F5C65
gpg: Can't check signature: public key not found
error: could not verify the tag 'v1.7.5'

出错原因是曾使用repo sync从其它库sync过代码，删掉~/.repoconfig即可：

$ rm -rf ~/.repoconfig
$ ./repo init -u git://github.com/CyanogenMod/android.git -b gingerbread
gpg: keyring `/home/calvin/.repoconfig/gnupg/secring.gpg' created
gpg: keyring `/home/calvin/.repoconfig/gnupg/pubring.gpg' created
gpg: /home/calvin/.repoconfig/gnupg/trustdb.gpg: trustdb created
gpg: key 920F5C65: public key "Repo Maintainer <repo@android.kernel.org>" imported
gpg: Total number processed: 1
gpg:               imported: 1

Getting repo ...
   from http://android.git.kernel.org/tools/repo.git
。。。。

2.repo sync时报错：

......
Fetching projects:   1% (3/285) 
Initializing project platform/bootable/bootloader/legacy ...
android.git.kernel.org[0: 130.239.17.13]: errno=Connection refused
android.git.kernel.org[0: 149.20.4.77]: errno=Connection timed out
android.git.kernel.org[0: 199.6.1.173]: errno=Connection refused
android.git.kernel.org[0: 2001:4f8:8:10:1972:112:1:0]: errno=Network is unreachable
android.git.kernel.org[0: 2001:500:60:10:1972:112:1:0]: errno=Network is unreachable
android.git.kernel.org[0: 2001:6b0:e:4017:1972:112:1:0]: errno=Network is unreachable
android.git.kernel.org[0: 2001:4f8:1:10:1972:112:1:0]: errno=Network is unreachable
fatal: unable to connect a socket (Network is unreachable)
error: Cannot fetch platform/bootable/bootloader/legacy

连接服务器时的问题，解决：
修改.repo/manifest.xml中

  <remote  name="korg"
           fetch="git://android.git.kernel.org/"
           review="review.source.android.com" />

为

  <remote  name="korg"
           fetch="http://android.git.kernel.org/"
           review="review.source.android.com" />