<SOLVED>Newb: Installed Mint but cannot boot without inserting iommu=soft in place of quiet splash

[ZSM]

Hi there,

These and other Linux forums have been very helpful working through several issues, but am finally stuck and need to post. Hope you can lend a hand!

I have installed Linux Mint 19 Cinnamon with kernel 4.15.0-42 generic.

It is installed on a Lenovo Ideapad 330s. The "inxi" readout is:
CPU~Quad core AMD Ryzen 5 2500U with Radeon Vega Mobile Gfx (-MT-MCP-) speed/max~1297/2000 MHz Kernel~4.15.0-42-generic x86_64 Up~24 min Mem~961.4/6856.5MB HDD~128.0GB(15.2% used) Procs~241 Client~Shell inxi~2.3.56

When originally booting from a USB to perform an installation, I needed to do so in compatibility mode. I disabled secure boot.

After installing, I rebooted and was not able to proceed past a blank screen. I tried several different edits to the grub boot screen (I think that's what it is called) which I think disable graphics drivers or applied a vega driver (e.g., "nomodeset" in place of "quiet splash"). These unfortunately did not work in my case.

What did work was deleting "quiet splash" and inserting "iommu=soft". I am not sure what that command does - my search for an answer suggests it has something to do with memory management.

Anyway, Linux Mint will boot from the hard drive when I edit that iommu=soft parameter into the grub.

After booting, I was able to get wifi working by installing the driver for the Realtek rtl8821ec adapter using the advice in this thread: viewtopic.php?t=276656.

I then updated everything in the "Update Manager". I sought to update drivers, but the "Driver Manager" indicates no proprietary drivers are in use.

I did add "synaptics" drivers to allow the touchpad of this laptop to work.

At this point, whenever I try to boot (whether from a shutdown or a restart), I get a black screen (no cursor in the top left, and ctrl+alt+del has no effect). I am only able to boot by powering down, then holding down "shift" and then edit the grub to replace "quiet splash" with 'iommu=soft" each time while booting.

Would be very grateful for any assistance!

Thanks a lot.

Zak

[ajgringo619]

My Gigabyte motherboard has similar issues. If I don't disable IOMMU (in the BIOS) and add iommu=soft, I can't use any of my USB3 ports. In fact, when I first installed Mint, I had to move my mouse/keyboard to USB2 ports. Do you have IOMMU enabled in the BIOS?

Question: is everything working with the iommu=soft switch?

[smurphos]

I everything works OK with iommu=soft then you can make that permanent by editing /etc/default/grub via sudo nano /etc/defaut/grub in a terminal and amending the line GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to GRUB_CMDLINE_LINUX_DEFAULT="iommu=soft quiet splash" saving then running sudo update-grub

Shouldn't need to remove quiet splash but you can if you want.

https://github.com/spotify/linux/blob/m ... s.txt#L207 gives an overview of the effect of the iommu=soft option.

[ZSM]

Hi smurphos, thank you, that was very helpful instruction. I made the permanent change to the grub and now the machine boots fine. I didn't know how to do that. I also appreciated the link to the boot options documentation -- hadn't seen that before.

Hi ajgringo619 - as far as I can tell, it is working OK with the iommu=soft switch, including the USB. Thanks for pointing that out as a possible issue for me to check. I was not able to see a way to change the iommu setting in the BIOS of this computer, however.

I am inferring from the responses (and the description of the iommu=soft setting in boot options document linked by smurphos) that there is nothing wrong with the installation or machine simply because I need the iommu=soft setting for it to boot. If there are possible issues I should check, please let me know. In the mean time, seems to be all OK.

Thanks for the help!

Zak

[smurphos]

I am inferring from the responses (and the description of the iommu=soft setting in boot options document linked by smurphos) that there is nothing wrong with the installation or machine simply because I need the iommu=soft setting for it to boot. If there are possible issues I should check, please let me know. In the mean time, seems to be all OK.

It's pretty new hardware and support in the linux kernel isn't mature yet. In a couple of months you should have the option to install a newer kernel series via update manager. Once that happens it would be worth checking if it boots without that option.