Blacklisting/ignoring primary video card

Discussion in 'Other Operating Systems' started by schnappy, Jun 19, 2020.

  1. schnappy

    schnappy Member

    Joined:
    Apr 23, 2008
    Messages:
    884
    Location:
    3124
    Hi,

    I have an Asus Rampage IV Extreme mobo with two video cards. The top slot (GTX1070) is what the BIOS and Linux want to use, and the BIOS has no option to set the boot video device (/initial video output). The second slot has an AMD RX480.

    I want to boot into Linux and use only the RX480 with amdgpu. Currently I can only get Linux to boot and Xorg to start with amdgpu blacklisted. For convoluted reasons I need the GTX1070 in the top slot so I can't change this, I know this is the easy and obvious fix. I also want to use the GTX1080 for VFIO so blacklisting nvidia/nouveau is fine by me.

    Is this possible? If the BIOS doesn't have a way to specify which device to use then I seem to be forced to use the top slot as my video output device in GRUB but then I want Linux to be oblivious to it...

    *should* having amdgpu and such in my mkinitcpio work? With blacklists for nouveau etc. So far no luck but I am still trying.

    Thanks

    Edit: Magic words for Google are 'pass through boot GPU' -- plenty of results. Will work through those.
     
    Last edited: Jun 19, 2020
  2. GumbyNoTalent

    GumbyNoTalent Member

    Joined:
    Jan 8, 2003
    Messages:
    9,832
    Location:
    Briz Vegas
    schnappy back in the dim dark ages, laptops discrete graphics and GPU had a wild time with switching, will have a look thru my notes when I get home and throw a AMD R270 in with my Nvidia 1660GT and see what it says for you as this is an interesting and unusual issue.

    Do you run both under Windows without issue?
     
  3. OP
    OP
    schnappy

    schnappy Member

    Joined:
    Apr 23, 2008
    Messages:
    884
    Location:
    3124
    They work fine together in Windows, and in Xorg too unless I try and mess with what is the primary for VFIO.

    Here is a pretty easy read on a few pieces of the puzzle:
    https://passthroughpo.st/explaining-csm-efifboff-setting-boot-gpu-manually/

    Looks like I'll set up a desktop manager, no big deal I am often impressed at how polished Fedora 31 is on my laptop.

    What I can't find a good indication of is whether it is possible to have a graphical prompt for dm-crypt? Everything but my /boot partition is encrypted. I know Fedora has a graphical prompt for your passphrase but I don't think that is graphical in the same sense (Admittedly I only have half a clue what I am saying here).
     
  4. GumbyNoTalent

    GumbyNoTalent Member

    Joined:
    Jan 8, 2003
    Messages:
    9,832
    Location:
    Briz Vegas
    schnappy so your all good on the GPU front?
     
  5. OP
    OP
    schnappy

    schnappy Member

    Joined:
    Apr 23, 2008
    Messages:
    884
    Location:
    3124
    I did some messing around last night, baby steps to try and avoid having to boot from a USB and do a disaster recovery. I'll do a write up when I make notable progress.

    If I add amdgpu to the module list in my mkinitcpio I have both video cards working before my root is decrypted which is promising.
     

Share This Page

Advertisement: