ubuntu12.04无法正常关机，哪位大侠能解决？
我之前用11.10时也有这种问题，出现过关机不断电的情况，解决后又出现无法关机，显示end trace后面跟一串数字，然后要长按电源键强制关机。。。后来我换了10.10，不装更新和驱动，问题就解决了。。前几天又换了12.04，装了显卡驱动后问题又出现了。。。我怀疑是显卡驱动的问题，我的是华硕F81s的本子，显卡是A卡。装系统时就很麻烦，要关闭acpi才能安装启动。。。我先在把显卡驱动卸载掉了，问题还是有。别说什么init 0 或者 shutdown -h一类的命令，我都试过了。求高人指点迷津啊！！！！感激不尽！！！！

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acpi=off pci=nomsi 网上有人说这两个选项同时用，不知道你用了可以不。把它加到grub的启动选项试试吧。https://bugs.launchpad.net/ubuntu/+source/acpi/+bug/695580

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如果不行，参考一下这个文档 http://www.brighthub.com/computing/linux/articles/39504.aspx#secn_2 里面的说明，测试一下acpi的哪个选项出的问题。如果只是某个acpi的选项用不了，那就禁止这个子选项好了，最后写到grub启动的内核参数里面就可以了。
Probable Solution

Slide 2 of 8
The first thing you will want to look at when experiencing shutdown problems is ACPI (Advanced Configuration and Power Interface). This, in my experience, is the most common culprit when it comes to Linux shutdown problems. When troubleshooting ACPI, please follow the steps below:
Try booting with the "acpi=off" kernel parameter: This will disable ACPI support. If the error is the same with acpi enabled and disabled, you are probably not having an ACPI issue. If that is the case, please see the section of this article titled "Other Possible Solutions".
If "acpi=off" allows the system to boot, you will need to isolate the ACPI issue by trying each of the following boot parameters.
Try booting with "acpi=ht": This disables all of ACPI except just enough to enable Hyper Threading. If acpi=off works and acpi=ht fails, then the issue is in the ACPI table parsing code itself, or perhaps the SMP code.
Try booting with "pci=noacpi": This disables ACPI for IRQ routing and PCI scanning.
Try booting with "acpi=noirq": This disables ACPI for IRQ routing.
Try booting with "pnpacpi=off": This disables the ACPI component of the Linux Plug and Play code.
Try booting with "noapic": This disables the IO-APIC for IRQ routing or PCI scanning.
Try booting with "nolapic": This disables the local APIC.
With any luck one of these extra boot parameters has solved your problem with Ubuntu hanging on shutdown. If not, ACPI was not the problem and we'll need to look at other possible solutions. Please skip ahead to "Other Possible Solutions". If one or more of these boot parameters solved your problem with Ubuntu hanging on shutdown consult the next section on how to make the changes permanent.

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网上还有人说bios 里面设置开启了APM (Advanced Power Management)。

内核对应的参数是，有好几电源开关相关的，自己去看一下内核参数说明。不过我看这个是 acpi之前的电源管理模块来的，能用acpi还是用acpi吧，不知道这个久的你的电脑是不是也有支持的。

 373 apm= [APM] Advanced Power Management
 374 See header of arch/x86/kernel/apm_32.c.