我在为Beaglebone Debian加载uart端口时遇到问题。
以下是我的配置：
我在Debian OS上拥有beaglebone。我有一个带有4个分区的SD卡。
分区1（mmcblk0p1）包含以下引导加载程序配置：-
分区2（mmcblk0p2）包含Debian OS。
分区3（mmcblk0p3）包含另一个Debian OS。
分区4（mmcblk0p4）决定从哪个分区启动？
/ mmcblk0p1中的/uEnv.txt从mmcblk0p4中读取并确定要从哪个分区启动。
这是我的/uEnv.txt：
rdaddr=0x88080000
initrd_high=0xffffffff
fdt_high=0xffffffff
loadxrd=echo debug: [/boot/initrd.img-${uname_r}] ... ; load mmc 0:1 ${rdaddr} /boot/initrd.img-${uname_r}; setenv rdsize ${filesize}
loaduEnvtxt=load mmc 0:1 ${loadaddr} /boot/uEnv.txt ; env import -t ${loadaddr} ${filesize};
check_dtb=if test -n ${dtb}; then setenv fdtfile ${dtb};fi;
check_uboot_overlays=if test -n ${enable_uboot_overlays}; then setenv enable_uboot_overlays ;fi;
loadall=run loaduEnvtxt; run check_dtb; run check_uboot_overlays; run loadxrd;
rootpart=0:2
flagpart=0:4
bootdir=/boot
bootfile=vmlinuz-4.14.71-ti-r80
console=ttyO0,115200n8
fdtaddr=0x88000000
fdtfile=am335x-bonegreen-wireless.dtb
loadaddr=0x82000000
mmcroot=/dev/mmcblk0p2 ro
mmcrootfstype=ext4 rootwait
mmcargs=setenv bootargs console=${console} ${optargs} ${cape_disable} ${cape_enable} root=${mmcroot} rootfstype=${mmcrootfstype} ${cmdline}
loadfdt=echo debug: [/boot/dtbs/${uname_r}/${fdtfile}] ... ;load mmc 0:1 ${fdtaddr} /boot/dtbs/${uname_r}/${fdtfile}
loadimage=echo debug: [/boot/vmlinuz-${uname_r}] ... ; load mmc 0:1 ${loadaddr} /boot/vmlinuz-${uname_r}
boot_three=setenv rootpart 0:3; setenv mmcroot /dev/mmcblk0p3 ro
findroot=\
if test -e mmc $flagpart three; then \
if test -e mmc $flagpart three_ok; then \
run boot_three; \
elif test ! -e mmc $flagpart three_tried; then \
fatwrite mmc $flagpart $loadaddr three_tried 4; \
run boot_three; \
fi; \
elif test -e mmc $flagpart two; then \
if test ! -e mmc $flagpart two_ok; then \
if test -e mmc $flagpart two_tried; then \
run boot_three; \
else \
fatwrite mmc $flagpart $loadaddr two_tried 4; \
fi; \
fi; \
fi;
uenvcmd=\
run loadall; \
run findroot; \
echo Using root partition ${rootpart}; \
if run loadfdt; then \
echo Loaded ${fdtfile}; \
if run loadimage; then \
run mmcargs; \
bootz ${loadaddr} - ${fdtaddr}; \
fi; \
fi;
在/boot/uEnv.txt中，我启用了以下配置：
uname_r=4.14.71-ti-r80
enable_uboot_overlays=1
uboot_overlay_addr0=/lib/firmware/BB-UART4-00A0.dtbo
uboot_overlay_addr1=/lib/firmware/BB-UART1-00A0.dtbo
uboot_overlay_addr2=/lib/firmware/BB-I2C2-00A0.dtbo
uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-14-TI-00A0.dtbo
enable_uboot_cape_universal=1
cmdline=coherent_pool=1M net.ifnames=0 quiet
我的启动日志：
U-Boot SPL 2018.09-00002-g0b54a51eee (Sep 10 2018 - 19:41:39 -0500)
Trying to boot from MMC2
Loading Environment from EXT4...
** Unable to use mmc 0:1 for loading the env **
U-Boot 2018.09-00002-g0b54a51eee (Sep 10 2018 - 19:41:39 -0500), Build: jenkins-github_Bootloader-Builder-65
CPU : AM335X-GP rev 2.1
I2C: ready
DRAM: 512 MiB
No match for driver 'omap_hsmmc'
No match for driver 'omap_hsmmc'
Some drivers were not found
Reset Source: Power-on reset has occurred.
RTC 32KCLK Source: External.
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
Loading Environment from EXT4...
** Unable to use mmc 0:1 for loading the env **
Board: BeagleBone Black
<ethaddr> not set. Validating first E-fuse MAC
BeagleBone Black:
Model: SeeedStudio BeagleBone Green Wireless:
BeagleBone: cape eeprom: i2c_probe: 0x54:
BeagleBone: cape eeprom: i2c_probe: 0x55:
BeagleBone: cape eeprom: i2c_probe: 0x56:
BeagleBone: cape eeprom: i2c_probe: 0x57:
Net: eth0: MII MODE
Could not get PHY for cpsw: addr 0
cpsw, usb_ether
Press SPACE to abort autoboot in 2 seconds
board_name=[A335BNLT] ...
board_rev=[GW1A] ...
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
60067 bytes read in 6 ms (9.5 MiB/s)
gpio: pin 56 (gpio 56) value is 0
gpio: pin 55 (gpio 55) value is 0
gpio: pin 54 (gpio 54) value is 0
gpio: pin 53 (gpio 53) value is 1
switch to partitions #0, OK
mmc0 is current device
gpio: pin 54 (gpio 54) value is 1
Checking for: /uEnv.txt ...
2628 bytes read in 2 ms (1.3 MiB/s)
gpio: pin 55 (gpio 55) value is 1
Loaded environment from /uEnv.txt
Importing environment from mmc ...
Checking if uenvcmd is set ...
gpio: pin 56 (gpio 56) value is 1
Running uenvcmd ...
2113 bytes read in 3 ms (687.5 KiB/s)
debug: [/boot/initrd.img-4.14.71-ti-r80] ...
4799493 bytes read in 303 ms (15.1 MiB/s)
Using root partition 0:2
debug: [/boot/dtbs/4.14.71-ti-r80/am335x-bonegreen-wireless.dtb] ...
60067 bytes read in 8 ms (7.2 MiB/s)
Loaded am335x-bonegreen-wireless.dtb
debug: [/boot/vmlinuz-4.14.71-ti-r80] ...
10416640 bytes read in 652 ms (15.2 MiB/s)
## Flattened Device Tree blob at 88000000
Booting using the fdt blob at 0x88000000
Using Device Tree in place at 88000000, end 88011aa2
Starting kernel ...
[ 0.000749] timer_probe: no matching timers found
[ 0.783193] wkup_m3_ipc 44e11324.wkup_m3_ipc: could not get rproc handle
[ 1.073624] omap_voltage_late_init: Voltage driver support not added
[ 1.080550] PM: Cannot get wkup_m3_ipc handle
问题：
现在，当我启动分区并检查UART端口时，找不到它们。
ls -l /dev/ttyO*
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO0 -> ttyS0
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO2 -> ttyS2
我期望的输出是：
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO0 -> ttyS0
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO1 -> ttyS1
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO2 -> ttyS2
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO3 -> ttyS3
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO4 -> ttyS4
lrwxrwxrwx 1 root root 5 Nov 3 2016 /dev/ttyO5 -> ttyS5