Ubuntu 19.10 Doesn't Ship With AMD Navi / Radeon RX 5700 Support Working, But Easy To Enable
While the principal driver components of the Linux kernel and Mesa3D (for RadeonSI OpenGL and RADV Vulkan) are new enough with Navi support, Ubuntu 19.10's support isn't rounded out because its linux-firmware package isn't new enough for containing the necessary Navi firmware binaries required for the open-source driver usage. So if booting a clean Ubuntu 19.10 install with Radeon RX 5700, you are likely to just see a blank screen.
Fortunately, with the firmware just lacking, it's easy to round out the support. After booting with "nomodeset" to get to a display, SSH'ing in, or similar, fetching and making use of the latest linux-firmware.git bits are as easy as:
git clone git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
sudo cp -va amdgpu/ /lib/firmware/
sudo update-initramfs -u
After that, the Radeon RX 5700 series should be lighting up with the default Linux 5.3 and Mesa 19.2 driver stack. It's unfortunate the Radeon Navi firmware wasn't landed for making the official Ubuntu 19.10 ISO. I've been waiting to see if the Navi firmware would come down as a stable release update, but so far it has not -- thus today's PSA. Several Phoronix readers had already written in wondering why their new Navi graphics cards aren't lighting up when booting to the Ubuntu 19.10 image.
Linux 5.3 and Mesa 19.2 are new enough but if finding the performance coming up short or hitting stability issues, you may want to upgrade to the latest Mesa RadeonSI/RADV drivers via the likes of the Oibaf PPA. Newer kernels are available from the Ubuntu Mainline Kernel PPA.