作者：付汉杰 hankf@amd.com
错误
PetaLinux编译Microblaze的U-Boot时，遇到下列错误 ，链接时提示找不到相关函数。
| microblazeel-xilinx-linux-ld.bfd -Bstatic --no-dynamic-linker -Ttext 0x80100000 -o u-boot -T u-boot.lds arch/microblaze/cpu/start.o --start-group arch/microblaze/cpu/built-in.o arch/microblaze/lib/built-in.o board/xilinx/microblaze-generic/built-in.o cmd/built-in.o common/built-in.o disk/built-in.o drivers/built-in.o drivers/dma/built-in.o drivers/gpio/built-in.o drivers/i2c/built-in.o drivers/net/built-in.o drivers/net/phy/built-in.o drivers/power/built-in.o drivers/power/battery/built-in.o drivers/power/domain/built-in.o drivers/power/fuel_gauge/built-in.o drivers/power/mfd/built-in.o drivers/power/pmic/built-in.o drivers/power/regulator/built-in.o drivers/serial/built-in.o drivers/spi/built-in.o drivers/usb/cdns3/built-in.o drivers/usb/common/built-in.o drivers/usb/dwc3/built-in.o drivers/usb/emul/built-in.o drivers/usb/eth/built-in.o drivers/usb/host/built-in.o drivers/usb/musb-new/built-in.o drivers/usb/musb/built-in.o drivers/usb/phy/built-in.o drivers/usb/ulpi/built-in.o dts/built-in.o env/built-in.o fs/built-in.o lib/built-in.o net/built-in.o --end-group -L /proj/hankf/ac701-microblaze-peta-202/build/tmp/work/microblazeel_v11.0_bs_cmp_mh_div_generic-xilinx-linux/u-boot-xlnx/v2020.01-xilinx-v2020.2+gitAUTOINC+bb4660c33a-r0/recipe-sysroot/usr/lib/microblazeel-xilinx-linux/9.2.0 -lgcc -Map u-boot.map; true
| microblazeel-xilinx-linux-ld.bfd: cmd/built-in.o: in function `format_mac_pxe':
| /proj/hankf/ac701-microblaze-peta-202/build/tmp/work/microblazeel_v11.0_bs_cmp_mh_div_generic-xilinx-linux/u-boot-xlnx/v2020.01-xilinx-v2020.2+gitAUTOINC+bb4660c33a-r0/git/cmd/pxe_utils.c:49: undefined reference to `eth_get_dev_index'
| microblazeel-xilinx-linux-ld.bfd: /proj/hankf/ac701-microblaze-peta-202/build/tmp/work/microblazeel_v11.0_bs_cmp_mh_div_generic-xilinx-linux/u-boot-xlnx/v2020.01-xilinx-v2020.2+gitAUTOINC+bb4660c33a-r0/git/cmd/pxe_utils.c:49: undefined reference to `eth_env_get_enetaddr_by_index'
| make[1]: *** [/proj/hankf/ac701-microblaze-peta-202/build/tmp/work/microblazeel_v11.0_bs_cmp_mh_div_generic-xilinx-linux/u-boot-xlnx/v2020.01-xilinx-v2020.2+gitAUTOINC+bb4660c33a-r0/git/Makefile:1671: u-boot] Error 1
| make[1]: Leaving directory '/proj/hankf/ac701-microblaze-peta-202/build/tmp/work/microblazeel_v11.0_bs_cmp_mh_div_generic-xilinx-linux/u-boot-xlnx/v2020.01-xilinx-v2020.2+gitAUTOINC+bb4660c33a-r0/build'
| make: *** [Makefile:167: sub-make] Error 2
| make: Leaving directory '/proj/hankf/ac701-microblaze-peta-202/build/tmp/work/microblazeel_v11.0_bs_cmp_mh_div_generic-xilinx-linux/u-boot-xlnx/v2020.01-xilinx-v2020.2+gitAUTOINC+bb4660c33a-r0/git'
| WARNING: /proj/hankf/ac701-microblaze-peta-202/build/tmp/work/microblazeel_v11.0_bs_cmp_mh_div_generic-xilinx-linux/u-boot-xlnx/v2020.01-xilinx-v2020.2+gitAUTOINC+bb4660c33a-r0/temp/run.do_compile.44657:1 exit 1 from 'exit 1'
解决办法
方法1
函数“eth_get_dev_index”在网络代码里定义，使能CONFIG_NET后才会被编译。
hankf@XSZGS4:u-boot-xlnx$ grep -rn eth_get_dev_index
include/net.h:241:int eth_get_dev_index(void); /* get the device index */
cmd/pxe_utils.c:49: if (!eth_env_get_enetaddr_by_index("eth", eth_get_dev_index(), ethaddr))
net/eth_legacy.c:94:int eth_get_dev_index(void)
net/net.c:1394: int num = eth_get_dev_index();
net/eth-uclass.c:175:int eth_get_dev_index(void)
net/cdp.c:154: sprintf(buf, CONFIG_CDP_PORT_ID, eth_get_dev_index());
hankf@XSZGS4:u-boot-xlnx$ grep -rn eth-uclass.c
Binary file .git/index matches
drivers/net/Kconfig:12: This is currently implemented in net/eth-uclass.c
hankf@XSZGS4:u-boot-xlnx$ grep -rn eth-uclass.o
net/Makefile:14:obj-$(CONFIG_NET) += eth-uclass.o
检查工程，发现U-Boot没有使能“Networking Support” （CONFIG_NET）。
There is no help available for this option.
Symbol: NET [=y]
Type : bool
Prompt: Networking support
Defined at net/Kconfig:5
执行“petalinux-config -c u-boot”， 选择“Networking Support”， 再编译，能通过。
方法2
嵌入式系统里，一般不使用PXE，应该可以不编译pxe_utils.c。
搜索“pxe_utils.o”，发现它被下列两个配置项引用。
obj-$(CONFIG_CMD_PXE) += pxe.o pxe_utils.o
obj-$(CONFIG_CMD_SYSBOOT) += sysboot.o pxe_utils.o
检查对应的配置项，发现“CONFIG_CMD_SYSBOOT”被“DISTRO_DEFAULTS”使能。
CONFIG_CMD_SYSBOOT:
Boot image via local extlinux.conf file
Symbol: CMD_SYSBOOT [=y]
Type : bool
Prompt: sysboot Location:
-> Command line interface
-> Misc commands
Defined at cmd/Kconfig:1689
Selects: MENU [=y]
Selected by [y]:
- DISTRO_DEFAULTS [=y]
禁止“DISTRO_DEFAULTS”，“CONFIG_CMD_SYSBOOT”， ， 再编译，能通过。
