Iommu=soft inside /etc/default/grub for Gigabyte 970 gaming

I found that the line GRUB_CMDLINE_LINUX_DEFAULT= (must have added) " … iommu=soft" at /etc/default/grub

And I have just discovered that after purchasing a Gigabyte 970 gaming mainboard with the AMD 8350FX CPU (cheap and good enough for me).

And not having ethernet connection with Manjaro and with the liveISO.

I suppose if the LiveISO adds this iommu=soft the ethernet would work, or if this iommu=soft, is not all right for all the boards with iommu, some kind of detection in order to change this parameter to those (I suppose this is not the only one) that need this change or option.

If no change is made, at least I hope that this post will help others. and remember to update grub after editing that line.

All the 970 boards are the same but there is a lot of confusion. on the implementation, If you set the iommu controller to onn the default is off and don’t use USB3 ports you don’t need to add that line at all. it will boot from USB2 but it is best if you use default off and add that line, if you don’t distro hop, I do then its a pain on every live usb disro to add the line.

…and sadly, that’s how Gigabyte had treated their IOMMU for AM3±9xx-MB-chipsets. :wink:
BTW, this issue has been known, within Gigabyte, in Linux, since atleast 2012, and they NEVER fixed it.

However, you could also try this: (after “Enabling” [SVM], and [IOMMU Controller] in uefi/bios):
In Linux:
instead of just “iommu=soft”

“amd_iommu=on iommu=pt” and all your usb2/3 ports, Lan, and Wifi will still work.
this remaps the AMDvT iommu, but mileage may vary in virtualization.

1 Like

Yep I had the 700 series before still usb3 non of this hassle but the audio chipset went faulty within the 3 years warranty and they sent me this one to replace and of course no ide controller so my plexwriter is now in the spare parts draw not that I need to use it? :joy:

Thanks a lot, I did not find this solution, that as is better that what i found I want to make it more visible for further visitors:


“amd_iommu=on iommu=pt”

you need to mark it as solved by @scjet tick the solved button on his post

1 Like

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.