27 January 2005

Reset lost BIOS password - Virtual Server 2005

An answer to a question that came up on the internal Microsoft discussion group for Virtual Server 2005 amused me. The question was what could you do if you lost the BIOS password for a virtual machine.

In a physical machine, you can often move a jumper on the motherboard or remove the battery to reset the CMOS. Obviously a virtual machine doesn't have anything physical like this, but the answer posted up was to "remove the virtual battery". You can't, although I did look through the .vmc (Virtual Machine Configuration) file for a battery setting :-)

The actual answer is simply to open the .vmc file in a text editor, and scan down to the <bios> section which will be similar to below:

<bios>
    <base_board>
        <serial_number type="string">1234-5678-4797-4379-2023-2540-66</serial_number>
     </base_board>
     <bios_guid type="string">{5242D6D9-20F8-7442-B2E6-DFCFFC45749A}</bios_guid>
     <bios_serial_number type="string">1234-5678-4797-4379-2023-2540-66</bios_serial_number>
     <chassis>
         <asset_tag type="string">1234-5678-4797-4379-2023-2540-66</asset_tag>
         <serial_number type="string">1234-5678-4797-4379-2023-2540-66</serial_number>
     </chassis>
     <time_bytes type="bytes">55000100100005270105</time_bytes>
     <cmos type="bytes">00004000F02....truncated...000000</cmos>
</bios>

If you remove the highlighted line above starting "<cmos" and restart your Virtual Machine, the password will be gone (as will any other customisations made to your BIOS). Note that this file is locked while the Virtual Machine is running, and this should also work under Microsoft Virtual PC 2004 as the .VMC file is largely compatible between the two products.

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Comments

# Eric Balk said:
I am having some other problems with Virtual Server 2005 and find this article interesting for the fact that there is a discussion group for Virtual Server 2005.

Where can i find that?
27 January 05 at 12:40 PM
# John Howard [MSFT] said:
Eric - I was referring to an internal to Microsoft discussion group. There is an external newsgroup publicly available through news.microsoft.com (if your ISP doesn't have a news server) by the name of microsoft.public.virtualserver.

This is also available through the web at http://support.microsoft.com/newsgroups/newsReader.aspx?lang=en&cr=US&dg=microsoft.public.virtualserver&sloc=en-us.

You can also try me :-)
27 January 05 at 12:51 PM
# david said:
awef
28 January 05 at 7:31 AM
# david said:
awef
28 January 05 at 7:32 AM
# david said:
awef
28 January 05 at 7:32 AM
# grat said:
use Bochs!
29 January 05 at 11:13 PM
# Welcome to Flaphead.com @ Home said:
31 January 05 at 6:27 AM
# TrackBack said:
02 February 05 at 6:53 AM
# jelly said:
hi. i just have a vhd image file. how do i access the configuration file, .vmc.
17 February 05 at 7:19 AM
# John Howard [MSFT] said:
A guest cannot run without a .vmc file - the .vhd file is just the hard disk. You can create a new guest and add your hard disk to it, in which case there isn't an BIOS password to be reset.
17 February 05 at 8:12 AM
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