vga_get_grc
int vga_get_grc(int, int);
reg[3] = vga_get_grc(VGA_REG_BASE, VGA_GC_READ_MAP_SELECT);
reg[4] = vga_get_grc(VGA_REG_BASE, VGA_GC_MODE);
reg[5] = vga_get_grc(VGA_REG_BASE, VGA_GC_MISCELLANEOUS);