Edit cmos settings from dos

Discussion in 'BIOS Mods' started by Stannieman, Jun 17, 2010.

  1. Stannieman

    Stannieman MDL Guru

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    I found out that my cpu supports AMD-V hardware virtualisation and dep, but both are disabled in bios and there is no such option shown in the bios menu. I know it's possible to make changes to the cmos settings programmatically with a dos bootdisk. So if it's only hidden in the bios menu, but the bios still contains this feature, then it should be possible to dump the cmos data and write it back after moddification, right?
    And if something goes wrong I think I can just load setup defaults and everything is fine again?

    I dumped my cmos settings with cmossave (only first 128 bytes of it), but I really don't know where to start.
    I also don't know if it's possible to do this without the bios complaining about bad checksums afterwards.
    Anyone who can help me?

    Bios bin and cmos dump can be downloaded from the link below. The bios was backed up with the award version of winflash because the pheonix version didn't work, but that shouldn't matter I guess?

    http://www.mediafire.com/file/enlykzjnqgm/CMOSEDIT.rar

    Thanks in advance!!
     
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  2. NoJuan999

    NoJuan999 Experienced SLIC Tool Operator

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  3. Stannieman

    Stannieman MDL Guru

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    [​IMG]
    This is the virtualisation option in modbin, it's set to disabled so it isn't visible in the setup screen. It's default is enabled but actually it's off, maybe because the option is disabled in the setup screen?

    [​IMG]
    This is a screenshot of cmos features, could 1 of the 2 black xxxxx refer to the cmos space where the amd-v setting is stored? Black means disabled.

    I don't want to flash me bios rom, but since the option is available and just hidden from the menu it should be possible to change that bit in the cmos dumb and place that dump in cmos again. At least when the setting is stored within the first 128bytes
     
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  4. NoJuan999

    NoJuan999 Experienced SLIC Tool Operator

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    It may work but you need to read all you can about Editing CMOS Settings in Memory, I have never seen it done but good luck.
    You would have to set it up so that memory setting was edited every time the PC Boots.

    Why not just set the menu item to Normal in ModBin and save it then flash the BIOS with the new menu item shown ????
     
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  5. Stannieman

    Stannieman MDL Guru

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    Bacause I'm a bit scared for a badflash. This is our only pc at home except for an old crappy one without internet connection (upt is port borken), so if I brick it everyone will be really angry at me... And why would I need to change it on every bootup? Isn't the cmos only cleared when you take out the mainboard batery or when you load setup defaults?
     
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  6. Stannieman

    Stannieman MDL Guru

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    This was what I'm talking about:
    http://www.linuxformat.gr/?q=content/how-unlock-and-enable-hardware-accelerated-virtualization-technology-vt-sony-vaio-laptop-and
    This is for intel vt but it should be possible for amsd-v also I think.

    And uhm... A'm I still correct if I say that cmos really isn't the bios rom itself that you update with a bios flash? In that case the author of that guid isn't correct cause he says it involves bios flashing and risk for bricking. He only reads from the rom and writes to the cmos.
     
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  7. NoJuan999

    NoJuan999 Experienced SLIC Tool Operator

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    While CMOS and BIOS are indeed NOT the same thing, the CMOS is usually cleared and updated when you Flash a BIOS.
    Read this:
    http://www.computerhope.com/issues/ch000707.htm

    You would have to figure out exactly where the specific setting you want to change gets placed in Physical memory by the CMOS at Bootup and make that change at every boot up.
    Which as I have stated I have Never even heard of this being done.

    OR you have to Flash the modified BIOS, which will change the settings on the CMOS chip.
    It seems to me that you need to do a LOT more research before you attempt any of this.
     
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  8. Stannieman

    Stannieman MDL Guru

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    I don't need to change the setting in memory at every bootup, neither I have to flash the bios.
    If I use symcmos to make another dump of the cmos then I have to find where the option is in that dump (disassembling the bios). The I use symcmos to place the edited cmos dump back to the cmos chip. No bios flashing and nothing needed every bootup.

    But the guide is for intel cpus ans I've amd, so I don't know after which values I have to search in the bios.
     
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  9. NoJuan999

    NoJuan999 Experienced SLIC Tool Operator

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    #9 NoJuan999, Jun 18, 2010
    Last edited: Jun 18, 2010
    I don't think it actually works without the BIOS Settings getting changed.
    It looks like by using symcmos, you are technically Flashing (clearing and Rewriting) the CMOS Settings of the BIOS.
    I think it would be safer and easier to just enable the setting in ModBin.
    Just be sure to read the ModBin Guide linked in the Bios Tools thread.
     
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  10. Stannieman

    Stannieman MDL Guru

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    #10 Stannieman, Jun 19, 2010
    Last edited: Jun 19, 2010
    (OP)
    OK what's the risk for a bad flash when I make a dos cd with award flash tool and moddid bin file, and disconnect all hardware except for keyboard and screen?
    And is there any chance the bios gets corrupted because the bin gets corrupted during modding?

    My bios screen shows "Pheonix technologies AWARD 6.00GP", so deos it matter what tools I use (award or phoenix)?
     
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  11. urie

    urie Moderator
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    You use award tool.
     
  12. Stannieman

    Stannieman MDL Guru

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    I think I'm just leaving it as it is, afterall I've heard that amd-v and intel vt don't bring very much performance improvement over software virtualisation.
     
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