Make grub menu readable on high-resolution screens

When grub loads on my work laptop, a DELL XPS 17 9710, the font is tiny and practically unreadable.

You can change the font of this screen.

From /etc/default/grub:

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

To find the available resolutions on your machine, boot into the grub menu and press C to enter console mode. Then type vbeinfo. Look for the list of available resolutions and choose one.

I went with 640x480, which meant I only had to uncomment the GRUB_GFXMODE line.

Then run sudo update-grub to save the change. Reboot and you should be able to read the screen.