我正在使用Ubuntu 12.04.2 LTS。
我正在尝试通过apt-get upgrade方法使用内核升级所有软件包。
但是，我收到以下消息：

Reading package lists… Done
Building dependency tree
Reading state information… Done
The following packages have been kept back:
linux-headers-virtual linux-image-virtual mysql-client-5.5 mysql-server-5.5
mysql-server-core-5.5
The following packages will be upgraded:
base-files dosfstools linux-libc-dev linux-libc-dev:i386
4 upgraded, 0 newly installed, 0 to remove and 5 not upgraded.
Need to get 1,847 kB of archives.
After this operation, 2,048 B of additional disk space will be used.
Do you want to continue [Y/n]?

如何解决此问题并安装linux-headers-virtual linux-image-virtual软件包，这些软件包已保留在Ubuntu Linux LTS 12.04.2版中？
如果您正在运行虚拟或者云镜像，则无需获取更新的启用堆栈，因此建议保留在原始的Precise堆栈上。
您仅在以下情况下需要更新的内核

• 您需要在现有LTS发行版上支持各种硬件，默认情况下12.04.2和更高版本的发行版将附带更新的内核和X堆栈。
• 这些较新的硬件支持堆栈将由较新的内核和来自12.10(定量)，13.04(竞赛)，13.10(Saucy)和14.04(T名称TBD)的X堆栈组成。
• 这些启用堆栈目前仅打算在x86硬件上使用。

如果您确实要升级虚拟/云镜像，请尝试：

$ sudo apt-get dist-upgrade

输出示例：

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following NEW packages will be installed:
  libterm-readkey-perl linux-headers-3.2.0-52 linux-headers-3.2.0-52-virtual
  linux-image-3.2.0-52-virtual
The following packages will be upgraded:
  base-files dosfstools linux-headers-virtual linux-image-virtual
  linux-libc-dev linux-libc-dev:i386 mysql-client-5.5 mysql-server-5.5
  mysql-server-core-5.5
9 upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
Need to get 50.2 MB of archives.
After this operation, 102 MB of additional disk space will be used.
Do you want to continue [Y/n]? y
....
....
..
Searching for GRUB installation directory ... found: /boot/grub
Searching for default file ... found: /boot/grub/default
Testing for an existing GRUB menu.lst file ... found: /boot/grub/menu.lst
Searching for splash image ... none found, skipping ...
Found kernel: /vmlinuz-3.2.0-52-virtual
Found kernel: /vmlinuz-3.2.0-31-virtual
Found kernel: /memtest86+.bin
Replacing config file /run/grub/menu.lst with new version
Updating /boot/grub/menu.lst ... done

Setting up libterm-readkey-perl (2.30-4build3) ...
Setting up mysql-client-5.5 (5.5.32-0ubuntu0.12.04.1) ...
Setting up mysql-server-core-5.5 (5.5.32-0ubuntu0.12.04.1) ...
Setting up mysql-server-5.5 (5.5.32-0ubuntu0.12.04.1) ...
Installing new version of config file /etc/apparmor.d/usr.sbin.mysqld ...
mysql start/running, process 1013
Setting up dosfstools (3.0.12-1ubuntu1.1) ...
Setting up linux-headers-3.2.0-52 (3.2.0-52.78) ...
Setting up linux-headers-3.2.0-52-virtual (3.2.0-52.78) ...
Setting up linux-headers-virtual (3.2.0.52.62) ...
Setting up linux-image-virtual (3.2.0.52.62) ...

您需要重新启动基于Ubuntu的系统，执行：

# reboot