Try https://wiki.archlinux.org/index.php/Grub#Visual_Configuration .
Shortly: $ sudo hwinfo --framebuffer and set the desired resolution in /etc/default/grub , "GRUB_GFXMODE".
Try https://wiki.archlinux.org/index.php/Grub#Visual_Configuration .
Shortly: $ sudo hwinfo --framebuffer and set the desired resolution in /etc/default/grub , "GRUB_GFXMODE".