Very strange USB stuff

[computerguy]

Recently in helping a friend with his PC I installed Ubuntu Mate for him.
All went well - except that his USB3 ports didn't work - but everything else does & he has no need for USB3, so no biggie.

Now the shoe is on the other foot because I'm making a PC up for my own uses now & this USB mess is even stranger - the USB3 ports work, but none of the USB2 ports do ?!?

Being the curious sort I've tried using the USB2 ports for live booting & whenever it is an Ubuntu variant - it works for a time, then pauses or halts with the message:
"(initrams)Unable to find a medium containing a live file system"

Doing the same with the USB3 ports Ubuntu variants boot fine.

Moving right along, I tried several other live booting sticks (Partition Wizard, etc.) & they all boot 100% fine using the USB2 ports.

Searching here for related threads yielded only these that I could find:

My as yet totally beguiling USB problem

Hello everyone, I’ve held off from posting on this kind of forum up until now and have searched high and low on the google for a resolution. I used to run Ubuntu 14.04.2 on my old desktop (MSI MS-7250 motherboard) and then I tried to upgrade. There was a problem with the graphics card which I couldn’t resolve to I installed Ubuntu Mate to work alongside it and managed to save all my data. However, on starting to use Mate none of my USB ports worked. I now am keen to use my USB ports for all s…

USB 3.0 not working

I don’t really know how long it’s been going on. About a week or so ago the error message finally piqued by curiosity with, “I wonder what that means?” Before that, it didn’t register, so I don’t know when it first appeared. After I finally noticed it, that’s when I started trying to figure out what it meant. Here the output of sudo dmesg | grep -i usb: jim@jim-pc:~$ sudo dmesg | grep -i usb [sudo] password for jim: [ 0.341245] ACPI: bus type USB registered [ 0.341259] usbcore: regis…

More info:
inxi -SMCD
System: Host: home
Kernel: 4.15.0-45-generic x86_64 bits: 64
Desktop: MATE 1.20.1
Distro: Ubuntu 18.04.1 LTS
Machine:
Device: desktop System: Gigabyte product: N/A serial: N/A
Mobo: Gigabyte model: 970A-DS3P v: x.x serial: N/A
BIOS: American Megatrends v: FD date: 02/26/2016
CPU: 6 core AMD FX-6300 Six-Core (-MCP-) cache: 12288 KB
clock speeds: max: 3500 MHz 1: 3219 MHz 2: 2603 MHz 3: 3101 MHz
4: 3148 MHz 5: 1436 MHz 6: 1408 MHz
Drives: HDD Total Size: 351.7GB (4.3% used)
ID-1: /dev/sda model: WDC_WD3200AAJS size: 320.1GB

I hope some folks here have a clue what may be out of kilter & how I may fix this ?!?
The PC is recently built with all new parts, so hopefully this is fixable via software, somehow.
Thanks.

[Dave_Barnes]

Search for "iommu" in the forum.

Also see:

AMD System fresh install , Only USB 3 working (IOMMU?)

djb

[computerguy]

Dave_Barnes you are amazing - sincerest thanks !!!
Both are working now.
I also did another test by enabling the IOMMU setting & that caused the opposite response - so USB2 worked & 3 did not.

What concerns me presently is that I will be using windows in a VM on my new CPU, and I will be attaching physical HDD partitions to my VM - so when I read here:

What is IOMMU and will it improve my VM performance?

And here:

Input–output memory management unit

That it may be important to have enabled, well - now I am again concerned & wonder if this is the only solution ??

If anyone can further educate me about IOMMU I will hugely appreciate the help !!
Thanks.

[computerguy]

BTW, I did search here & generally for djb, but didn't see anything related with these USB related problems ??

Thanks.