Impossible to install Ubuntu 18.04 on a new computer

Question

I'm trying to install Ubuntu on a brand new computer but I can't get it done. I'm getting a lot of lines like :

AMD-VI: Completion-Wait loop timed out

or

---[ end Kernel panic - not syncing: Fatal exception in interrupt

I've recreated my Ubuntu USB key 4 or 5 times with different software and support without any luck. I modified the iommu to disabled but no change. I installed Windows 10 without trouble, and everything is working fine there.

Motherboard: b350 PC MATE
CPU: Ryzen 5 2600X
GPU: radeon RX 570

Some screenshots of my issue:

iso md5 is ok, legacy support in bios is on. I tried nomodetest, acpi=off and nolapic as suggested in this post.

Did you verify the download was valid? (https://tutorials.ubuntu.com/tutorial/tutorial-how-to-verify-ubuntu) — guiverc, Aug 30 '18 at 07:36
@karel This is a kernel panic according to the screenshots, I don’t think this case is included in the canonical question. — Melebius, Aug 30 '18 at 07:52
This is a problem with bugged firmware. Try to enable legacy support and boot your flash drive on UEFI. "I modified the iommu to disabled" Don't, if you do that you need to install a 32-bit system. — Rinzwind, Aug 30 '18 at 07:52
@guiverc I had no doubt about it but doesn't hurt to check. md5 is ok — ThEBiShOp, Aug 30 '18 at 07:58
@karel I tried with acpi=off, nolapic and nomodetest (nomodetest only didn't change the result), I'm reaching the ubuntu loading screen but stay stuck there — ThEBiShOp, Aug 30 '18 at 08:44

ThEBiShOp · Answer 1 · 2018-08-31T08:20:44.693

1

I managed to install and run Ubuntu by editing the commands before booting (e on the GRUB screen) and adding iommu=soft among quiet splash.

edit

Well, it partialy resolved my issue. I was able to install ubuntu, yes, but now I need to update the grub command each time I have a new kernel version. Plus my computer is not booting on grub, windows is. If I want to boot on linux, I need to enter my boot option and select my partition. I tried this post but had a message on boot repair : grub-efi-amd64-signed purge cancelled

edited Aug 31 '18 at 08:20

answered Aug 30 '18 at 10:21

ThEBiShOp

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After you boot to Ubuntu (by selecting the partition) edit the file /etc/default/grub and add the same iommu=soft after quiet splash. Save the file, and open a terminal and enter the following command: sudo update-grub. Let me know if this helps. – user68186 May 02 '19 at 21:39

Impossible to install Ubuntu 18.04 on a new computer

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