Keyboard and mouse not recognized when installing 18.04.3

Question

Have old computer running Windows 7: CPU - AMD FX-8350; Graphics Card - MSI AMD Radeon R7 240 - MB: GIGABYTE GA-990FXA-UD3 AM3; SSDs (2) - ADATA USA Premier Pro 2.5-Inch 128GB SATA III. Got Ubuntu, put on USB thumb drive and booted from thumb drive (Try without installing). Got to the desktop but old HP keyboard and mouse don't work. (Keyboard did work at boot menu.) Without rebooting, replaced them with newer Logitech keyboard and mouse. They worked.

Decided to install Ubuntu. Shut down, removed SSD with Windows and installed a clean SSD. Rebooted, selected Install from boot menu. Got background screen with window to select language but keyboard and mouse don't work.

Put computer back in original condition. Boots to Windows and keyboard and mouse work. Booted Ubuntu from USB stick, both Try without installing and Install, and keyboard and mouse don't work.

This is my first foray out of the Windows world. What am I missing?

Answer 1

With much help from others more knowledgeable than I, the following solution was found.

First, in the BIOS settings, under the Peripherals tab, you must set "IOMMU Controller" option to "Enabled". Without this setting, USB will not work at all under Linux. My understanding is that the integrated NIC will not work either, but I had it set properly before I got that far (I used a GParted live CD for partitioning prior to installation). USB mice and keyboards still work fine in the BIOS settings, so no worries making this simple change.

Secondly, once Linux is installed USB 3.0 ports will not work (they don't fall back to 2.0 or anything, they are just dead) until you add GRUB_CMDLINE_LINUX="iommu=soft" to /etc/default/grub and then run update-grub (Debian) or grub2-mkconfig (Red Hat) to apply the change.

This was from a review of the Gigabyte motherboard by David A. Jayne. For more details, see his complete review at https://www.amazon.com/GIGABYTE-GA-990FXA-UD3-990FX-SATA-Motherboard/dp/B00545BZOG