I solved these errors:
drivers/built-in.o:(.data+0×390): undefined reference to `fb_sys_read’
drivers/built-in.o:(.data+0×394): undefined reference to `fb_sys_write’
drivers/built-in.o:(.data+0x3b0): undefined reference to `sys_fillrect’
drivers/built-in.o:(.data+0x3b4): undefined reference to `sys_copyarea’
drivers/built-in.o:(.data+0x3b8): undefined reference to `sys_imageblit’
Just selecting CONFIG_FB_VIRTUAL
