ubuntu 升级至7.10后framebuffer console故障排除

症状：没有修改任何配置，升级后framebuffer console突然不工作了，纯控制台变成黑屏，手工加载fbcon, vesafb, nvidiafb（我的显卡是nvidia）也不行。

折腾了好半天，参考了一些网页，比如https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/129910

了解了大致原因，一个是 fbcon不能自动加载，另外是framebuffer的驱动被加入了blacklist

得解决方案：
1.修改/etc/initramfs-tools/modules, 添加fbcon, vesafb（每个模块占一行）
2.修改/etc/modprobe.d/blacklist-framebuffer, 把含vesafb, nvidiafb的两行注释掉
3.确认grub里的启动参数中设置好了vga

问题解决。

注：第一步里似乎不用加上nvidiafb, 但是另外两个似乎要加上

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