embedded-linux - 从美元卡启动时出错 - 没有文件系统可以挂载根目录，尝试了 :Ext4

Question

我正在尝试使用 Buildroot 构建一个在 PocketBeagle 上运行的嵌入式 Linux；并按照 ( source1 ) 中的说明进行操作。然后将生成的图像复制到美元卡。将美元卡插入 Pocketbeagle 并通过串行连接监控启动过程时；我收到以下错误:

No filesystem could mount root, tried: 
ext4
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,1)
---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,1).

使用的资源有:构建根目录:2018.02
文件系统:ext4
Bootloader:U-Boot(自定义版本2018.01)
内核版本:4.14.24
应用上述源中所述的所有补丁，可以在 ( source2 ) 中找到:
- 0001-Stripped-back-pocketbeagle-devicetree.patch
- 0001-am335x_evm-uEnv.txt-bootz-n-fixes.patch
- 0002-U-Boot-BeagleBone-Cape-Manager.patch
- 0003-pocketbeagle-tweaks.patch

运行构建会产生以下文件和图像:
MLO:第一阶段引导加载程序
U-boot.img:第二阶段引导加载程序
uEnv.txt:U-boot环境
zImage:Linux内核镜像
am335x-pocketbeagle.dtb:Linux 内核设备树 Blob
rootfs.ext4:根文件系统镜像

uEnv.txt如下:

fdtfile=am335x-pocketbeagle.dtb  
bootpart=0:1  
bootdir=  
bootargs=console=ttyO0,115200n8 root=/dev/mmcblk0p1 rw rootfstype=ext4   rootwait  
uenvcmd=run loadimage;run loadfdt;printenv bootargs;bootz ${loadaddr} - ${fdtaddr};  

然后通过在 buildroot 中使用genimage(并重建)来生成包含两个分区的美元镜像:
1. 包含引导加载程序镜像、内核镜像和设备树的 FAT 分区
2.包含根文件系统ext4的Rootfs分区

生成的图像称为sdcard.img，通过使用程序etcher (etcher-electron-1.4.3-x86_64.AppImage) 或通过(sudo dd if=output/images/sdcard.img of=/dev/mmcblk0 bs=1M)

我使用了两张不同的美元卡来测试构建，但结果是相同的:
1. 金士顿 32 GB (SDHC 10)
2.闪迪16GB(SDHC 10)

值得一提的是，我使用相同的 uSD 卡从 official site 加载 PocketBeagle 的原始镜像并从它们启动，卡启动没有问题。

任何有帮助的想法都将受到高度赞赏。

---

附录

日志文件中显示的另一个错误发生在启动开始时:

U-Boot SPL 2018.01 (Mar 24 2018 - 21:13:25) 
Trying to boot from MMC1 
*** Warning - bad CRC, using default environment 
reading u-boot.img 
reading u-boot.img 
U-Boot 2018.01 (Mar 24 2018 - 21:13:25 +0100) 
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. 
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1 
*** Warning - bad CRC, using default environment  

完整日志如下:

U-Boot SPL 2018.01 (Mar 24 2018 - 21:13:25)
Trying to boot from MMC1
*** Warning - bad CRC, using default environment

reading u-boot.img
reading u-boot.img


U-Boot 2018.01 (Mar 24 2018 - 21:13:25 +0100)

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.
MMC:   OMAP SD/MMC: 0, OMAP SD/MMC: 1
*** Warning - bad CRC, using default environment

Model: BeagleBoard.org PocketBeagle
<ethaddr> not set. Validating first E-fuse MAC
Net:   No ethernet found.
Press SPACE to abort autoboot in 2 seconds
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
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 ...
reading uEnv.txt
218 bytes read in 4 ms (52.7 KiB/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 ...
reading /zImage
5540120 bytes read in 351 ms (15.1 MiB/s)
loading /am335x-pocketbeagle.dtb ...
reading /am335x-pocketbeagle.dtb
33516 bytes read in 9 ms (3.6 MiB/s)
bootargs=console=ttyO0,115200n8 root=/dev/mmcblk0p1 rw rootfstype=ext4 rootwait
## Flattened Device Tree blob at 88000000
   Booting using the fdt blob at 0x88000000
   Loading Device Tree to 8fff4000, end 8ffff2eb ... OK

Starting kernel ...

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 4.14.24 (ammar@ammar-System-Product-Name) (gcc version 7.2.1 20171011 (Linaro GCC 7.2-2017.11)) #1 SMP Sat Mar 24 21:23:50 CET 2018
[    0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] OF: fdt: Machine model: TI AM335x PocketBeagle
[    0.000000] Memory policy: Data cache writeback
[    0.000000] cma: Reserved 16 MiB at 0x9e800000
[    0.000000] CPU: All CPU(s) started in SVC mode.
[    0.000000] AM335X ES2.1 (sgx neon)
[    0.000000] random: fast init done
[    0.000000] percpu: Embedded 17 pages/cpu @df93f000 s40872 r8192 d20568 u69632
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 129412
[    0.000000] Kernel command line: console=ttyO0,115200n8 root=/dev/mmcblk0p1 rw rootfstype=ext4 rootwait
[    0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[    0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[    0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[    0.000000] Memory: 479900K/522240K available (8192K kernel code, 810K rwdata, 2412K rodata, 1024K init, 7547K bss, 25956K reserved, 16384K cma-reserved, 0K highmem)
[    0.000000] Virtual kernel memory layout:
[    0.000000]     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
[    0.000000]     fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
[    0.000000]     vmalloc : 0xe0000000 - 0xff800000   ( 504 MB)
[    0.000000]     lowmem  : 0xc0000000 - 0xdfe00000   ( 510 MB)
[    0.000000]     pkmap   : 0xbfe00000 - 0xc0000000   (   2 MB)
[    0.000000]     modules : 0xbf000000 - 0xbfe00000   (  14 MB)
[    0.000000]       .text : 0xc0008000 - 0xc0900000   (9184 kB)
[    0.000000]       .init : 0xc0c00000 - 0xc0d00000   (1024 kB)
[    0.000000]       .data : 0xc0d00000 - 0xc0dca9b8   ( 811 kB)
[    0.000000]        .bss : 0xc0dcc000 - 0xc152af94   (7548 kB)
[    0.000000] Running RCU self tests
[    0.000000] Hierarchical RCU implementation.
[    0.000000]  RCU event tracing is enabled.
[    0.000000]  RCU lockdep checking is enabled.
[    0.000000]  RCU restricting CPUs from NR_CPUS=2 to nr_cpu_ids=1.
[    0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[    0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[    0.000000] IRQ: Found an INTC at 0xfa200000 (revision 5.0) with 128 interrupts
[    0.000000] OMAP clockevent source: timer2 at 24000000 Hz
[    0.000017] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
[    0.000044] clocksource: timer1: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635851949 ns
[    0.000097] OMAP clocksource: timer1 at 24000000 Hz
[    0.000569] timer_probe: no matching timers found
[    0.001470] Console: colour dummy device 80x30
[    0.001516] Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
[    0.001530] ... MAX_LOCKDEP_SUBCLASSES:  8
[    0.001542] ... MAX_LOCK_DEPTH:          48
[    0.001554] ... MAX_LOCKDEP_KEYS:        8191
[    0.001566] ... CLASSHASH_SIZE:          4096
[    0.001578] ... MAX_LOCKDEP_ENTRIES:     32768
[    0.001589] ... MAX_LOCKDEP_CHAINS:      65536
[    0.001601] ... CHAINHASH_SIZE:          32768
[    0.001613]  memory used by lock dependency info: 4655 kB
[    0.001626]  per task-struct memory footprint: 1536 bytes
[    0.001663] Calibrating delay loop... 996.14 BogoMIPS (lpj=4980736)
[    0.078740] pid_max: default: 32768 minimum: 301
[    0.079147] Security Framework initialized
[    0.079285] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.079306] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.082392] CPU: Testing write buffer coherency: ok
[    0.083889] CPU0: thread -1, cpu 0, socket -1, mpidr 0
[    0.085406] Setting up static identity map for 0x80100000 - 0x80100078
[    0.085975] Hierarchical SRCU implementation.
[    0.087625] smp: Bringing up secondary CPUs ...
[    0.087648] smp: Brought up 1 node, 1 CPU
[    0.087665] SMP: Total of 1 processors activated (996.14 BogoMIPS).
[    0.087679] CPU: All CPU(s) started in SVC mode.
[    0.091643] devtmpfs: initialized
[    0.116033] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[    0.116853] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.116916] futex hash table entries: 256 (order: 2, 16384 bytes)
[    0.118550] pinctrl core: initialized pinctrl subsystem
[    0.123225] NET: Registered protocol family 16
[    0.130326] DMA: preallocated 256 KiB pool for atomic coherent allocations
[    0.171692] omap_hwmod: debugss: _wait_target_disable failed
[    0.226390] cpuidle: using governor menu
[    0.237629] OMAP GPIO hardware version 0.1
[    0.262333] No ATAGs?
[    0.262360] hw-breakpoint: debug architecture 0x4 unsupported.
[    0.262655] omap4_sram_init:Unable to allocate sram needed to handle errata I688
[    0.262675] omap4_sram_init:Unable to get sram pool needed to handle errata I688
[    0.298256] edma 49000000.edma: TI EDMA DMA engine driver
[    0.303666] SCSI subsystem initialized
[    0.305374] omap_i2c 44e0b000.i2c: could not find pctldev for node /ocp/l4_wkup@44c00000/scm@210000/pinmux@800/pinmux_i2c0_pins, deferring probe
[    0.307447] omap_i2c 4802a000.i2c: bus 1 rev0.11 at 400 kHz
[    0.307764] omap_i2c 4819c000.i2c: could not find pctldev for node /ocp/l4_wkup@44c00000/scm@210000/pinmux@800/mma8452_pins_default, deferring probe
[    0.308058] pps_core: LinuxPPS API ver. 1 registered
[    0.308076] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="84e3edebe9e1f0f0edc4e8edeaf1fcaaedf0" rel="noreferrer noopener nofollow">[email protected]</a>>
[    0.308128] PTP clock support registered
[    0.312478] clocksource: Switched to clocksource timer1
[    0.448001] VFS: Disk quotas dquot_6.6.0
[    0.448193] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[    0.473020] NET: Registered protocol family 2
[    0.474843] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[    0.474948] TCP bind hash table entries: 4096 (order: 5, 147456 bytes)
[    0.476120] TCP: Hash tables configured (established 4096 bind 4096)
[    0.476506] UDP hash table entries: 256 (order: 2, 20480 bytes)
[    0.476689] UDP-Lite hash table entries: 256 (order: 2, 20480 bytes)
[    0.477446] NET: Registered protocol family 1
[    0.479566] RPC: Registered named UNIX socket transport module.
[    0.479614] RPC: Registered udp transport module.
[    0.479629] RPC: Registered tcp transport module.
[    0.479643] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    0.482107] hw perfevents: no interrupt-affinity property for /pmu, guessing.
[    0.483357] hw perfevents: enabled with armv7_cortex_a8 PMU driver, 5 counters available
[    0.487455] audit: initializing netlink subsys (disabled)
[    0.490304] audit: type=2000 audit(0.480:1): state=initialized audit_enabled=0 res=1
[    0.490640] workingset: timestamp_bits=14 max_order=17 bucket_order=3
[    0.493682] NFS: Registering the id_resolver key type
[    0.494058] Key type id_resolver registered
[    0.494099] Key type id_legacy registered
[    0.494253] jffs2: version 2.2. (NAND) (SUMMARY)  © 2001-2006 Red Hat, Inc.
[    0.500669] io scheduler noop registered
[    0.500700] io scheduler deadline registered
[    0.500822] io scheduler cfq registered (default)
[    0.500841] io scheduler mq-deadline registered
[    0.500856] io scheduler kyber registered
[    0.503256] pinctrl-single 44e10800.pinmux: 142 pins at pa f9e10800 size 568
[    0.510527] Serial: 8250/16550 driver, 6 ports, IRQ sharing enabled
[    0.516492] omap_uart 44e09000.serial: no wakeirq for uart0
[    0.516942] 44e09000.serial: ttyO0 at MMIO 0x44e09000 (irq = 30, base_baud = 3000000) is a OMAP UART0
[    1.250345] console [ttyO0] enabled
[    1.255586] omap_uart 48022000.serial: no wakeirq for uart1
[    1.261829] 48022000.serial: ttyO1 at MMIO 0x48022000 (irq = 31, base_baud = 3000000) is a OMAP UART1
[    1.272744] omap_uart 48024000.serial: no wakeirq for uart2
[    1.278844] 48024000.serial: ttyO2 at MMIO 0x48024000 (irq = 32, base_baud = 3000000) is a OMAP UART2
[    1.289570] omap_uart 481a8000.serial: no wakeirq for uart4
[    1.295781] 481a8000.serial: ttyO4 at MMIO 0x481a8000 (irq = 33, base_baud = 3000000) is a OMAP UART4
[    1.334046] brd: module loaded
[    1.362138] loop: module loaded
[    1.368162] mtdoops: mtd device (mtddev=name/number) must be supplied
[    1.383297] libphy: Fixed MDIO Bus: probed
[    1.390588] i2c /dev entries driver
[    1.398755] omap_hsmmc 48060000.mmc: Got CD GPIO
[    1.465093] ledtrig-cpu: registered to indicate activity on CPUs
[    1.472542] oprofile: using arm/armv7
[    1.477095] Initializing XFRM netlink socket
[    1.481985] NET: Registered protocol family 10
[    1.493215] Segment Routing with IPv6
[    1.497190] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[    1.505262] NET: Registered protocol family 17
[    1.509973] NET: Registered protocol family 15
[    1.515090] Key type dns_resolver registered
[    1.519724] omap_voltage_late_init: Voltage driver support not added
[    1.526481] sr_dev_init: No voltage domain specified for smartreflex0. Cannot initialize
[    1.535007] sr_dev_init: No voltage domain specified for smartreflex1. Cannot initialize
[    1.543566] ThumbEE CPU extension supported.
[    1.548049] Registering SWP/SWPB emulation handler
[    1.553116] SmartReflex Class3 initialized
[    1.623490] mmc0: host does not support reading read-only switch, assuming write-enable
[    1.635560] mmc0: new high speed SDHC card at address 0007
[    1.644119] mmcblk0: mmc0:0007 SD32G 28.8 GiB 
[    1.655081]  mmcblk0: p1 p2
[    1.671199] tps65217 0-0024: TPS65217 ID 0xe version 1.2
[    1.677649] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 400 kHz
[    1.686633] omap_i2c 4819c000.i2c: bus 2 rev0.11 at 400 kHz
[    1.694194] hctosys: unable to open rtc device (rtc0)
[    1.699490] sr_init: No PMIC hook to init smartreflex
[    1.705144] sr_init: platform driver register failed for SR
[    1.720670] List of all partitions:
[    1.724586] 0100           16384 ram0 
[    1.724597]  (driver?)
[    1.730999] 0101           16384 ram1 
[    1.731008]  (driver?)
[    1.737842] 0102           16384 ram2 
[    1.737854]  (driver?)
[    1.744389] 0103           16384 ram3 
[    1.744400]  (driver?)
[    1.750791] 0104           16384 ram4 
[    1.750800]  (driver?)
[    1.757269] 0105           16384 ram5 
[    1.757278]  (driver?)
[    1.763737] 0106           16384 ram6 
[    1.763746]  (driver?)
[    1.770139] 0107           16384 ram7 
[    1.770148]  (driver?)
[    1.776597] 0108           16384 ram8 
[    1.776607]  (driver?)
[    1.783061] 0109           16384 ram9 
[    1.783071]  (driver?)
[    1.789456] 010a           16384 ram10 
[    1.789465]  (driver?)
[    1.795999] 010b           16384 ram11 
[    1.796008]  (driver?)
[    1.802540] 010c           16384 ram12 
[    1.802549]  (driver?)
[    1.809029] 010d           16384 ram13 
[    1.809038]  (driver?)
[    1.815571] 010e           16384 ram14 
[    1.815580]  (driver?)
[    1.822056] 010f           16384 ram15 
[    1.822065]  (driver?)
[    1.828679] b300        30228480 mmcblk0 
[    1.828690]  driver: mmcblk
[    1.835867]   b301           16384 mmcblk0p1 00000000-01
[    1.835877] 
[    1.843044]   b302          524288 mmcblk0p2 00000000-02
[    1.843053] 
[    1.850164] No filesystem could mount root, tried: 
[    1.850173]  ext4
[    1.855340] 
[    1.858913] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,1)
[    1.867873] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,1)

---

Answer 1

由于未指定正确的SD卡分区，导致rootfs挂载失败。
在内核命令行中，(错误地)指示内核在/dev/mmcblk0p1对应的分区中查找rootfs。

bootargs=console=ttyO0,115200n8 root=/dev/mmcblk0p1 rw rootfstype=ext4 rootwait

和

[    0.000000] Kernel command line: console=ttyO0,115200n8 root=/dev/mmcblk0p1 rw rootfstype=ext4 rootwait

但是，mmc 子系统报告您的 SD 卡上有两个分区，并且启动日志会为您报告这些分区的设备名称​​两次。
第一:

[    1.635560] mmc0: new high speed SDHC card at address 0007
[    1.644119] mmcblk0: mmc0:0007 SD32G 28.8 GiB 
[    1.655081]  mmcblk0: p1 p2

然后:

[    1.720670] List of all partitions:
 ...
[    1.828679] b300        30228480 mmcblk0 
[    1.828690]  driver: mmcblk
[    1.835867]   b301           16384 mmcblk0p1 00000000-01
[    1.835877] 
[    1.843044]   b302          524288 mmcblk0p2 00000000-02

因此，内核命令行(通过 bootargs)应指定第二个分区 /dev/mmcblk0p2，而不是 rootfs 的第一个分区。

由于您的 U-Boot 环境的存储区域尚未正确初始化(即“警告 - CRC 错误，使用默认环境”消息)(或您的 uEnv.txt 文件丢失或损坏)，U-Boot 正在使用主板配置文件中定义的硬编码 bootargs 值启动 Linux 内核。
您可以编辑该文件并重新构建 U-Boot，或者中止自动引导并使用
setenv bootargs console=ttyO0,115200n8 root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait 和 saveenv 命令来纠正此错误规范。