我想知道为什么upgrade有时不想升级系统的某些部分，而dist-upgrade确实如此。这是运行后的示例apt-get upgrade：
apt-get upgrade：
rimmer@rimmer-Lenovo-IdeaPad-S10-2:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
linux-generic linux-headers-generic linux-image-generic
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.
与apt-get dist-upgrade：
rimmer@rimmer-Lenovo-IdeaPad-S10-2:~$ sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following NEW packages will be installed:
linux-headers-3.0.0-13 linux-headers-3.0.0-13-generic
linux-image-3.0.0-13-generic …不知何故，我得到了一个 12.04 服务器来停止更新内核。它停留在 3.2.0-24-generic 并且不想获取任何新的更新。目前的新内核是 3.2.0-29
apt-get clean && sudo apt-get autoremove
apt-get -f install
apt-get update
apt-get dist-upgrade
显示“0 升级，0 新安装，0 删除，0 未升级”。没有失败的安装。/var/log/aptitude 不显示任何错误
我的sources.list：
###### Ubuntu Main Repos
deb http://ca.archive.ubuntu.com/ubuntu/ precise main restricted
deb-src http://ca.archive.ubuntu.com/ubuntu/ precise main restricted
###### Ubuntu Update Repos
deb http://ca.archive.ubuntu.com/ubuntu/ precise-security main restricted
deb http://ca.archive.ubuntu.com/ubuntu/ precise-updates main restricted
deb-src http://ca.archive.ubuntu.com/ubuntu/ precise-security main restricted
deb-src http://ca.archive.ubuntu.com/ubuntu/ precise-updates main restricted
###### Ubuntu Partner Repo
deb http://archive.canonical.com/ubuntu precise partner
deb-src http://archive.canonical.com/ubuntu precise partner
有谁知道怎么了？谢谢