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Asus UEFI tells: "the VGA card is not supported by UEFI driver" and enables CSM (Compatibility Support Module: Legacy BIOS boot mode).

Enabling CSM doesn't make much sense as it won't help if you are using GPT or the OS requires UEFI to boot.

Background: I inserted an old ATI RV710 (HD 4x50) into my PC to build a multi-seat environment.

JPT
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  • Are you planning on answering this question yourself, or are you asking it for others to answer? – earthmeLon Oct 06 '18 at 03:19
  • @earthmeLon - I already answered it myself. But someone didn't like that I simply disabled security. So if you want to provide a solution with security still enabled, I would love to hear it. – – JPT Oct 13 '18 at 15:46

3 Answers3

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What it means is that the UEFI firmware detected a old video card without UEFI GOP code, so the CSM has been enabled to allow the legacy video BIOS code to be used. You can still boot in UEFI mode because UEFI GOP includes support for calling legacy video BIOS code through the CSM.

Yuhong Bao
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This just means that the UEFI mode BIOS does not fully support your video card, so it needs to enable CSM mode which can make it work using old BIOS mode controls. It's unfortunate, but not much you can do about it, just live with it.

You can still boot in UEFI mode, even though CSM compatibility is enabled.

Once the system is up this CSM mode does not really affect anything.

chutz
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  • Can you prove this? I don't think this is correct. As far as I read CSM means old BIOS boot procedure. You are right that once the system is up there won't be much difference. But you will have a problem if you have a GPT partition table. – JPT Oct 05 '18 at 18:03
  • @JPT For what it's worth, I am in the same situation. I got CSM compat mode forced on me due to VGA incompatibility, but the system does boot in UEFI mode. – chutz Oct 07 '18 at 07:30
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Cause: Secure Boot does not work with the driver used because it's not signed. Not sure why. As I did not install any additional ATI driver.

Solution: Disable Secure Boot. On my Asus Board I had to choose between "Windows" and "Other OS". Where Windows means Secure Boot is enabled, other - disabled. Great Naming.

You also should disable CSM. I don't understand why the UEFI automatically enabled CSM. As this does not help with the boot process if your system wants to boot via UEFI.

JPT
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  • Or self sign the driver - https://insights.ubuntu.com/2017/08/11/how-to-sign-things-for-secure-boot and https://askubuntu.com/questions/770205/how-to-sign-kernel-modules-with-sign-file . although disabling secure boot seems to be very popular -1 for disabling security features – Panther Mar 15 '18 at 15:47
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    Well, as far as I read.... UEFI security does not bring real security. It just prevents virus infections that did not expect security. – JPT Mar 18 '18 at 10:22
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    or makes it harder to install an operating system that isn't Windows. My laptop won't boot without so-called "secure" boot disabled – Zanna Sep 27 '18 at 16:23