Syslinux: change bootup resolution

To know which resolutions are supported by your screen, install hwinfo:

# pacman -S hwinfo

Then execute:

# hwinfo --vbe | grep 'Mode '

Modes are displayed in hexadecimal.

Now edit /boot/syslinux/syslinux.cfg and add to the APPEND line the desired resolution with:

vga=<resolution>

where <resolution> is the corresponding hexa code.

For example: add vga=0x037f if you want 1920x1080x24.