LOONGSON_UART_BASE depends on EARLY_PRINTK || SERIAL_8250, but when neither of these Kconfig symbols is set, the kernel build has errors: ../arch/mips/loongson2ef/common/serial.c: In function 'serial_init': ../arch/mips/loongson2ef/common/serial.c:66:25: error: 'loongson_uart_base' undeclared (first use in this function) 66 | loongson_uart_base; ../arch/mips/loongson2ef/common/serial.c:66:25: note: each undeclared identifier is reported only once for each function it appears in ../arch/mips/loongson2ef/common/serial.c:68:41: error: '_loongson_uart_base' undeclared (first use in this function) 68 | (void __iomem *)_loongson_uart_base; Fix this by building serial.o only when one (or both) of these Kconfig symbols is enabled. Tested with: (a) EARLY_PRINTK=y, SERIAL_8250 not set; (b) EARLY_PRINTK=y, SERIAL_8250=y; (c) EARLY_PRINTK=y, SERIAL_8250=m. (d) EARLY_PRINTK not set, SERIAL_8250=y; (e) EARLY_PRINTK not set, SERIAL_8250=m; (f) EARLY_PRINTK not set, SERIAL_8250 not set. Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Reported-by: kernel test robot <lkp@xxxxxxxxx> Cc: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxxx --- arch/mips/loongson2ef/common/Makefile | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- linext-20210803.orig/arch/mips/loongson2ef/common/Makefile +++ linext-20210803/arch/mips/loongson2ef/common/Makefile @@ -4,12 +4,14 @@ # obj-y += setup.o init.o env.o time.o reset.o irq.o \ - bonito-irq.o mem.o machtype.o platform.o serial.o + bonito-irq.o mem.o machtype.o platform.o obj-$(CONFIG_PCI) += pci.o # # Serial port support # +obj-$(CONFIG_LOONGSON_UART_BASE) += serial.o +obj-$(CONFIG_EARLY_PRINTK) += serial.o obj-$(CONFIG_LOONGSON_UART_BASE) += uart_base.o obj-$(CONFIG_LOONGSON_MC146818) += rtc.o
