Ubuntu 18.04 Won't Boot on Dell Inspiron 7375

I have the Ryzen 2700U Inspiron 7375 as well. I managed to get this working pretty well, however I had to get it installed using Antergos. I wasn't able to get it reliably booting under Ubuntu 18.04 unless I left acpi=off set in the kernel parameters and it wouldn't boot at all to the 4.17 kernel. I started trying different distributions and Antergos worked perfectly the first time (though I may have been lucky since afterwards it seemed 50/50).

After logs of digging and experimenting, I finally found these kernel parameters to be the key (using with linux kernel 4.17.2-1-zen from the Antergos linux-zen package):

amd_iommu=on ivrs_ioapic[4]=00:14.0 ivrs_ioapic[5]=00:00.2

Under Antergos I added these to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub then ran

sudo grub-mkconfig -o /boot/grub/grub.cfg

Now things are working pretty well! Maybe these options will help get things working under Ubuntu as well.

update: I just downloaded the 18.04 installer and tried to boot from it again (which comes with the 4.15 kernel). When I added the parameters above (by hitting 'e' on the bootloader) it was able to boot and work correctly. I didn't want to try an install over again so I didn't proceed further, but it appears to work correctly off of the live USB at least.

Looking through Dell's supported machines, there is an exclusivity towards intel machines. I have been attempting to get the same model machine with the Ryzen5 2500u to install any Debian based OS with no success. It may be that the new AMD architecture is still being incorporated into the Kernel. Additional research is required.

I'm hoping to get more answers as the Ryzen mobile series expands in popularity across vendors. It's actually the reason I bought a new laptop; I wanted to ride the new wave as AMD rushes to the field against the old king Intel.

Update

The ubuntu shipping kernel (4.15) does not have good support for AMD Raven Ridge CPUs. Supposedly 4.16 has better support but is not actively being shipped with Ubuntu.

Same problem on my Dell 7375. I found that removing "quiet" and "splash" and replacing with "noapic noacpi nosplash irqpoll" worked like a charm for me. It is what Linuxmint uses in the compatibilty mode. I have been able to boot both Ubuntu and Kubuntu. I intend on trying this with other distros as well, just cuz I like to play around with things.