我使用 Yocto 项目构建设备为我的 BeagleBoard xM（Rev C）构建了一个最小 Linux，并按照他们的说明将其安装在 uSD 卡上。
它很管用（耶！），占用空间小，启动速度非常快，这正是我想要的。考虑到这一点，我使用了一个非常简单的构建配方。
它给出了许多关于加载 USB 设备驱动程序的令人鼓舞的消息。但是，当我登录时，没有以太网接口，USB 上的其他任何东西似乎都无法工作。我尝试插入 USB 记忆棒，但它无法被识别（“dmesg”显示的日志中没有出现任何内容）。我也没有在显示屏上看到任何东西——我正在通过串行端口控制台进行交互。
我正在使用 Yocto 构建的 u-boot 二进制文件，并从同一源加载设备表 (dtb 文件) 和内核映像。但是，我注意到我拥有的 (工作) Debian 映像还包含一个“initrd”映像。借助 Debian 启动环境，我能够加载该 initrd (实际上是“uInitrd”，uboot 映像版本？)，但我仍然看不到 USB 设备。
我是不是漏掉了什么？我需要在 Yocto 构建中放入一些东西吗，还是它应该已经知道硬件了？鉴于我选择了“beagleboard”选项，我认为它知道要放入什么。我甚至需要“initrd”吗？根据我读过的文档，这是一个 ramdisk，它告诉内核要加载哪些驱动程序模块，但我不太明白。
这是从串行控制台复制的（整个！！）启动输出。我手动运行了 uBoot 命令来启动内核。
谢谢您的任何建议！
---------- UBOOT： -------------------------------------
U-Boot 2013.07 (Apr 02 2014 - 09:17:04)
OMAP36XX/37XX-GP ES1.2, CPU-OPP2, L3-165MHz, Max CPU Clock 1 Ghz
OMAP3 Beagle board + LPDDR/NAND
I2C: ready
DRAM: 512 MiB
NAND: 0 MiB
MMC: OMAP SD/MMC: 0
*** Warning - readenv() failed, using default environment
In: serial
Out: serial
Err: serial
Beagle xM Rev C
No EEPROM on expansion board
Die ID #2ed800029ff80000016849a906016009
musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
musb-hdrc: MHDRC RTL version 1.800
musb-hdrc: setup fifo_mode 4
musb-hdrc: 28/31 max ep, 16384/16384 memory
USB Peripheral mode controller at 480ab000 using PIO, IRQ 0
Net: usb_ether
Hit any key to stop autoboot: 0
OMAP3 beagleboard.org #
---------- UBOOT 命令：-----------------------------------------------------
OMAP3 beagleboard.org # setenv bootargs 'console=ttyO2,115200n8 root=/dev/mmcblk0p2 rootwait rootfstype=ext4 rw'
OMAP3 beagleboard.org # fatload mmc 0:1 0x80300000 zImage
reading zImage
4641688 bytes read in 296 ms (15 MiB/s)
OMAP3 beagleboard.org # fatload mmc 0:1 0x81600000 uInitrd;setenv initrd_size ${filesize}
reading uInitrd
3160554 bytes read in 205 ms (14.7 MiB/s)
OMAP3 beagleboard.org # fatload mmc 0:1 0x815f0000 beagle-xm.dtb
reading beagle-xm.dtb
11444 bytes read in 8 ms (1.4 MiB/s)
OMAP3 beagleboard.org # bootz 0x80300000 0x81600000:${initrd_size} 0x815f0000
---------- Linux 启动： ------------------------------------------------------
Kernel image @ 0x80300000 [ 0x000000 - 0x46d398 ]
## Loading init Ramdisk from Legacy Image at 81600000 ...
Image Name: initramfs
Image Type: ARM Linux RAMDisk Image (uncompressed)
Data Size: 3160490 Bytes = 3 MiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
## Flattened Device Tree blob at 815f0000
Booting using the fdt blob at 0x815f0000
Loading Ramdisk to 8fcfc000, end 8ffff9aa ... OK
Loading Device Tree to 8fcf6000, end 8fcfbcb3 ... OK
Starting kernel ...
Booting Linux on physical CPU 0x0
Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Initializing cgroup subsys cpuacct
Linux version 3.10.11-yocto-standard (builder@qemux86-64) (gcc version 4.8.1 (GCC) ) #1 Tue Apr 1 22:45:53 UTC 2014
CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c53c7d
CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
Machine: Generic OMAP3 (Flattened Device Tree), model: TI OMAP3 BeagleBoard xM
Memory policy: ECC disabled, Data cache writeback
DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map
CPU: All CPU(s) started in SVC mode.
OMAP3630 ES1.2 (l2cache iva sgx neon isp 192mhz_clk )
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 129792
Kernel command line: console=ttyO2,115200n8 root=/dev/mmcblk0p2 rootwait rootfstype=ext4 rw
PID hash table entries: 2048 (order: 1, 8192 bytes)
Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
allocated 1048576 bytes of page_cgroup
please try 'cgroup_disable=memory' option if you don't want memory cgroups
Memory: 511MB = 511MB total
Memory: 503688k/503688k available, 20600k reserved, 0K highmem
Virtual kernel memory layout:
vector : 0xffff0000 - 0xffff1000 ( 4 kB)
fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
vmalloc : 0xe0800000 - 0xff000000 ( 488 MB)
lowmem : 0xc0000000 - 0xe0000000 ( 512 MB)
pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
.text : 0xc0008000 - 0xc08ce880 (8987 kB)
.init : 0xc08cf000 - 0xc09512b4 ( 521 kB)
.data : 0xc0952000 - 0xc09e6fa0 ( 596 kB)
.bss : 0xc09e6fa0 - 0xc0aa0360 ( 741 kB)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
NR_IRQS:16 nr_irqs:16 16
IRQ: Found an INTC at 0xfa200000 (revision 4.0) with 96 interrupts
Total of 96 interrupts on 1 active controller
Clocking rate (Crystal/Core/MPU): 26.0/400/600 MHz
OMAP clockevent source: timer1 at 32768 Hz
sched_clock: 32 bits at 32kHz, resolution 30517ns, wraps every 131071999ms
OMAP clocksource: 32k_counter at 32768 Hz
Console: colour dummy device 80x30
Calibrating delay loop... 398.13 BogoMIPS (lpj=1990656)
pid_max: default: 32768 minimum: 301
Security Framework initialized
Mount-cache hash table entries: 512
Initializing cgroup subsys debug
Initializing cgroup subsys memory
Initializing cgroup subsys devices
Initializing cgroup subsys freezer
Initializing cgroup subsys net_cls
Initializing cgroup subsys blkio
CPU: Testing write buffer coherency: ok
ftrace: allocating 24224 entries in 72 pages
Setting up static identity map for 0xc060bdd0 - 0xc060be28
devtmpfs: initialized
xor: measuring software checksum speed
arm4regs : 745.200 MB/sec
8regs : 549.200 MB/sec
32regs : 716.000 MB/sec
xor: using function: arm4regs (745.200 MB/sec)
pinctrl core: initialized pinctrl subsystem
regulator-dummy: no parameters
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
Reprogramming SDRC clock to 400000000 Hz
OMAP GPIO hardware version 2.5
platform 49022000.mcbsp: alias fck already exists
platform 49024000.mcbsp: alias fck already exists
omap-gpmc 6e000000.gpmc: GPMC revision 5.0
hw-breakpoint: debug architecture 0x4 unsupported.
OMAP DMA hardware revision 5.0
bio: create slab <bio-0> at 0
raid6: int32x1 97 MB/s
raid6: int32x2 117 MB/s
raid6: int32x4 98 MB/s
raid6: int32x8 101 MB/s
raid6: using algorithm int32x2 (117 MB/s)
raid6: using intx1 recovery algorithm
omap-dma-engine 48056000.dma-controller: OMAP DMA engine driver
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
omap_i2c i2c.8: did not get pins for i2c error: -19
omap_i2c i2c.8: bus 0 rev4.4 at 2600 kHz
twl 0-0048: PIH (irq 23) chaining IRQs 338..346
twl 0-0048: power (irq 343) chaining IRQs 346..353
VDD1: 600 <--> 1450 mV at 1200 mV
VDAC: 1800 mV
VPLL2: 1800 mV
VMMC1: 1850 <--> 3150 mV at 3150 mV
VUSB1V5: 1500 mV
VUSB1V8: 1800 mV
VUSB3V1: 3100 mV
VSIM: 1800 <--> 3000 mV at 1800 mV
twl4030_gpio gpio.32: gpio (irq 338) chaining IRQs 354..371
omap_i2c i2c.9: did not get pins for i2c error: -19
omap_i2c i2c.9: bus 1 rev4.4 at 400 kHz
omap_i2c i2c.10: did not get pins for i2c error: -19
omap_i2c i2c.10: bus 2 rev4.4 at 100 kHz
Advanced Linux Sound Architecture Driver Initialized.
cfg80211: Calling CRDA to update world regulatory domain
Switching to clocksource 32k_counter
NET: Registered protocol family 2
TCP established hash table entries: 4096 (order: 3, 32768 bytes)
TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
TCP: reno registered
UDP hash table entries: 256 (order: 0, 4096 bytes)
UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
NET: Registered protocol family 1
RPC: Registered named UNIX socket transport module.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
Trying to unpack rootfs image as initramfs...
Freeing initrd memory: 3084K (cfcfc000 - cffff000)
hw perfevents: enabled with ARMv7 Cortex-A8 PMU driver, 5 counters available
NFS: Registering the id_resolver key type
Key type id_resolver registered
Key type id_legacy registered
bio: create slab <bio-1> at 1
Btrfs loaded
aufs 3.10-20130819
msgmni has been set to 989
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252)
io scheduler noop registered
io scheduler deadline registered
io scheduler cfq registered (default)
platform omapfb: Driver omapfb requests probe deferral
omap_uart serial.5: did not get pins for uart0 error: -19
serial.5: ttyO0 at MMIO 0x4806a000 (irq = 88) is a OMAP UART0
omap_uart serial.6: did not get pins for uart1 error: -19
serial.6: ttyO1 at MMIO 0x4806c000 (irq = 89) is a OMAP UART1
omap_uart serial.7: did not get pins for uart2 error: -19
serial.7: ttyO2 at MMIO 0x49020000 (irq = 90) is a OMAP UART2
console [ttyO2] enabled
omap_uart serial.17: did not get pins for uart3 error: -19
serial.17: ttyO3 at MMIO 0x49042000 (irq = 96) is a OMAP UART3
brd: module loaded
omap2_mcspi spi.11: pins are not configured from the driver
omap2_mcspi spi.12: pins are not configured from the driver
omap2_mcspi spi.13: pins are not configured from the driver
omap2_mcspi spi.14: pins are not configured from the driver
usbcore: registered new interface driver kaweth
pegasus: v0.9.3 (2013/04/25), Pegasus/Pegasus II USB Ethernet driver
usbcore: registered new interface driver pegasus
usbcore: registered new interface driver rtl8150
usbcore: registered new interface driver asix
usbcore: registered new interface driver ax88179_178a
usbcore: registered new interface driver cdc_ether
usbcore: registered new interface driver dm9601
usbcore: registered new interface driver smsc75xx
usbcore: registered new interface driver smsc95xx
usbcore: registered new interface driver net1080
usbcore: registered new interface driver cdc_subset
usbcore: registered new interface driver zaurus
usbcore: registered new interface driver MOSCHIP usb-ethernet driver
usbcore: registered new interface driver int51x1
usbcore: registered new interface driver cdc_ncm
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
ehci-omap: OMAP-EHCI Host Controller driver
ehci-omap 48064800.ehci: EHCI Host Controller
ehci-omap 48064800.ehci: new USB bus registered, assigned bus number 1
ehci-omap 48064800.ehci: irq 93, io mem 0x48064800
ehci-omap 48064800.ehci: USB 2.0 started, EHCI 1.00
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 3 ports detected
usbcore: registered new interface driver usb-storage
musb-hdrc musb-hdrc.0.auto: musb_init_controller failed with status -6
mousedev: PS/2 mouse device common for all mice
twl_rtc rtc.22: Power up reset detected.
twl_rtc rtc.22: Enabling TWL-RTC
twl_rtc rtc.22: rtc core: registered rtc.22 as rtc0
omap_wdt: OMAP Watchdog Timer Rev 0x31: initial timeout 60 sec
cpuidle: using governor ladder
cpuidle: using governor menu
omap-dma-engine 48056000.dma-controller: allocating channel for 62
omap-dma-engine 48056000.dma-controller: allocating channel for 61
omap_hsmmc mmc.15: pins are not configured from the driver
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
mmc0: host does not support reading read-only switch. assuming write-enable.
mmc0: new high speed SD card at address 0002
mmcblk0: mmc0:0002 00000 1.86 GiB
mmcblk0: p1 p2
omap-twl4030 sound.20: twl4030-hifi <-> 49022000.mcbsp mapping ok
oprofile: using arm/armv7
u32 classifier
Actions configured
TCP: cubic registered
NET: Registered protocol family 10
sit: IPv6 over IPv4 tunneling driver
NET: Registered protocol family 17
Key type dns_resolver registered
VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
ThumbEE CPU extension supported.
VUSB3V1: disabling
VPLL2: disabling
VDAC: disabling
platform omapfb: Driver omapfb requests probe deferral
console [netcon0] enabled
netconsole: network logging started
twl_rtc rtc.22: setting system clock to 2000-01-01 00:00:00 UTC (946684800)
ALSA device list:
#0: omap3beagle
Freeing unused kernel memory: 520K (c08cf000 - c0951000)
Loading, please wait...
udevd[71]: starting version 175
modprobe: chdir(3.10.11-yocto-standard): No such file or directory
Begin: Loading essential drivers ... done.
Begin: Running /scripts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
Begin: Running /scripts/local-premount ... done.
modprobe: chdir(3.10.11-yocto-standard): No such file or directory
EXT4-fs (mmcblk0p2): recovery complete
EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
Begin: Running /scripts/local-bottom ... done.
done.
Begin: Running /scripts/init-bottom ... done.
INIT: version 2.88 booting
Error opening /dev/fb0: No such file or directory
Starting Bootlog daemon: bootlogd.
EXT4-fs (mmcblk0p2): re-mounted. Opts: data=ordered
Configuring network interfaces... ifconfig: SIOCGIFFLAGS: No such device
ifconfig: SIOCGIFFLAGS: No such device
Wed Apr 2 09:19:00 UTC 2014
INIT: Entering runlevel: 5
Starting system message bus: dbus.
Starting Dropbear SSH server: dropbear.
Starting syslogd/klogd: done
Stopping Bootlog daemon: bootlogd.
Poky (Yocto Project Reference Distro) 1.5 beagleboard /dev/ttyO2
beagleboard login: root
root@beagleboard:~# ifconfig -a
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
sit0 Link encap:IPv6-in-IPv4
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
root@beagleboard:~#
答案1
事实证明，内核构建的扁平设备树 (.dtb) 实际上已损坏。而且，它没有必要。我只是删除了它，并删除了在 u 启动环境文件 (uEnv.txt) 中加载它的行。我的 Beagleboard 现在可以正常启动，并且有 USB 设备（我已经测试了以太网和 USB 大容量存储）。
还需注意的是，Yocto 有一个官方的 meta-beagleboard 层，可以从以下网址下载：这里。虽然我还没有真正尝试过，但这在 Beagle 上应该会更可靠地工作。