Linux+SD卡(rootfs)（二）

Linux+SD卡(rootfs)

busybox 下载链接：https://busybox.net/
下载

wget https://busybox.net/downloads/busybox-1.36.1.tar.bz2

解压

 tar -vxf busybox-1.36.1.tar.bz2 

并进入其根目录

export ARCH=arm
export CROSS_COMPILE=arm-none-linux-gnueabihf-
make defconfig
make menuconfig
#   勾选  Settings-> [*] Build static binary (no shared libs)
make -j6
make install

上述步骤执行完后在 busybox 根目录生成了一个 _install 文件夹。
随便找一个目录，来创建 linux 的根文件系统

# 随便找一个目录，创建 linux 的根文件系统
cd rootfs

# 将 _install 的所有文件拷贝到 rootfs 文件夹中
cp -r /home/tyustli/code/open_source/busybox/busybox-1.36.1/_install/* ./

# 复制库文件
mkdir lib
cp -r /home/tyustli/cross_tool/gcc-arm-10.3-2021.07-x86_64-arm-none-linux-gnueabihf/lib/* lib/

# 创建设备节点
mkdir dev
cd dev
# 创建多个 tty 设备，注意子设备号不要重复
sudo mknod -m 666 tty1 c 4 1
sudo mknod -m 666 tty2 c 4 2
sudo mknod -m 666 tty3 c 4 3
sudo mknod -m 666 tty4 c 4 4
sudo mknod -m 666 tty5 c 4 5
sudo mknod -m 666 tty6 c 4 6
# 创建一个控制台节点
sudo mknod -m 666 console c 5 1
# 创建一个空节点
sudo mknod -m 666 null c 1 3

cd ../../
# 生成虚拟 SD 卡系统镜像
sudo dd if=/dev/zero of=rootfs.ext3 bs=1M count=32
# 格式化镜像
sudo mkfs.ext3 rootfs.ext3

#将根文件系统中的文件复制到镜像中
sudo mkdir tmpfs # 创建一个临时目录
sudo mount -t ext3 rootfs.ext3 tmpfs/ -o loop # 将 rootfs.ext3 镜像挂载到 tmpfs 目录下
sudo cp -r rootfs/*  tmpfs/ # 将  rootfs 目录下所有文件拷贝到 tmpfs 目录下，即拷贝的到 rootfs.ext3 镜像中
sudo umount tmpfs # 将临时挂载的文件系统卸载掉

上面的步骤执行完后，rootfs.ext3 镜像中就包含了 rootfs 目录下的所有内容，此时linux的根文件系统就已经制作完成，下一步就是使用这个 rootfs.ext3 镜像来启动 linux 内核

linux 启动文件

sudo qemu-system-arm -M vexpress-a9 -m 512M -kernel arch/arm/boot/zImage -dtb arch/arm/boot/dts/arm/vexpress-v2p-ca9.dtb -nographic \
-append "root=/dev/mmcblk0 rw console=ttyAMA0" -sd /home/tyustli/code/open_source/busybox/rootfs.ext3

这里比之前多指定了一个 sd 镜像。
linux 启动日志

 #0: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 37
input: ImExPS/2 Generic Explorer Mouse as /devices/platform/bus@40000000/bus@40000000:motherboard-bus@40000000/bus@40000000:motherboard-bus@40000000:iofpga@7,00000000/10007000.kmi/serio1/input/input2
drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111
EXT4-fs (mmcblk0): mounting ext3 file system using the ext4 subsystem
EXT4-fs (mmcblk0): mounted filesystem b28f1697-44d3-4ac5-879c-fffa4116c9cc r/w with ordered data mode. Quota mode: disabled.
VFS: Mounted root (ext3 filesystem) on device 179:0.
Freeing unused kernel image (initmem) memory: 1024K
Run /sbin/init as init process
random: crng init done
can't run '/etc/init.d/rcS': No such file or directory

Please press Enter to activate this console. 
~ # drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111
amba 1000f000.wdt: deferred probe pending
amba 10020000.clcd: deferred probe pending
amba 100e0000.memory-controller: deferred probe pending
amba 100e1000.memory-controller: deferred probe pending
amba 100e5000.watchdog: deferred probe pending
i2c 0-0039: deferred probe pending

~ # ls
bin         lib         lost+found  usr
dev         linuxrc     sbin
~ # 

报错一

can't run '/etc/init.d/rcS': No such file or directory

解决

mkdir etc
cd etc
mkdir init.d
cd init.d
touch rcS
chmod 777 rcS

# 向文件中写入内容
cat > rcS <<EOF
#!/bin/sh
ATH=/sbin:/bin:/usr/sbin:/usr/bin
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/lib:/usr/lib
export PATH LD_LIBRARY_PATH runlevel
mount -a
mkdir /dev/pts
mount -t devpts devpts /dev/pts
mdev -s
EOF

报错二

can't run '/etc/init.d/rcS': Permission denied

解决

chmod 777 rcS

创建好文件 /etc/init.d/rcS 以后一定要给其可执行权限！

报错三

mount: can't read '/etc/fstab': No such file or directory
/etc/init.d/rcS: line 8: can't create /proc/sys/kernel/hotplug: nonexistent directory
mdev: /sys/dev: No such file or directory

解决

cd etc
touch fstab
# 向文件中写入内容
cat > fstab <<EOF
#   
proc  /proc proc  defaults 00
tmpfs /tmp  tmpfs defaults 00
sysfs /sys  sysfs defaults 00
EOF

附录：根文件系统制作完整脚本

cd rootfs

cp -r /home/tyustli/code/open_source/busybox/busybox-1.36.1/_install/* ./

# 复制库文件
mkdir lib
cp -r /home/tyustli/cross_tool/gcc-arm-10.3-2021.07-x86_64-arm-none-linux-gnueabihf/lib/* lib/

# 创建设备节点
mkdir dev
cd dev
sudo mknod -m 666 tty1 c 4 1
sudo mknod -m 666 tty2 c 4 2
sudo mknod -m 666 tty3 c 4 3
sudo mknod -m 666 tty4 c 4 4
sudo mknod -m 666 tty5 c 4 5
sudo mknod -m 666 tty6 c 4 6
# 创建一个控制台节点
sudo mknod -m 666 console c 5 1
# 创建一个空节点
sudo mknod -m 666 null c 1 3

cd ../
mkdir etc
mkdir proc
mkdir tmp
mkdir sys
cd etc
touch fstab
# 向文件中写入内容
cat > fstab <<EOF
#   
proc  /proc proc  defaults 00
tmpfs /tmp  tmpfs defaults 00
sysfs /sys  sysfs defaults 00
EOF

touch inittab
cat > inittab<<EOF
#etc/inittab
::sysinit:/etc/init.d/rcS
console::askfirst:-/bin/sh
::restart:/sbin/init
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::shutdown:/sbin/swapoff -a
EOF

mkdir init.d
cd init.d
touch rcS
chmod 777 rcS

# 向文件中写入内容
cat > rcS <<EOF
#!/bin/sh
ATH=/sbin:/bin:/usr/sbin:/usr/bin
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/lib:/usr/lib
export PATH LD_LIBRARY_PATH runlevel
mount -a
mkdir /dev/pts
mount -t devpts devpts /dev/pts
# echo /sbin/mdev >/proc/sys/kernel/hotplug
mdev -s
EOF

cd ../../../
# 生成虚拟 SD 卡系统镜像
sudo dd if=/dev/zero of=rootfs.ext3 bs=1M count=32
# 格式化镜像
sudo mkfs.ext3 rootfs.ext3

#将文件复制到镜像中
sudo mkdir tmpfs
sudo mount -t ext3 rootfs.ext3 tmpfs/ -o loop
sudo cp -r rootfs/*  tmpfs/
sudo umount tmpfs
rmdir tmpfs

linux 内核启动完整日志

WARNING: Image format was not specified for '/home/tyustli/code/open_source/busybox/rootfs.ext3' and probing guessed raw.
         Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
         Specify the 'raw' format explicitly to remove the restrictions.
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib pcm_dmix.c:1032:(snd_pcm_dmix_open) unable to open slave
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `lm4549.out'
Booting Linux on physical CPU 0x0
Linux version 6.5.7 (tyustli@tyustli-machine) (arm-none-linux-gnueabihf-gcc (GNU Toolchain for the A-profile Architecture 10.3-2021.07 (arm-10.29)) 10.3.1 20210621, GNU ld (GNU Toolchain for the A-profile Architecture 10.3-2021.07 (arm-10.29)) 2.36.1.20210621) #3 SMP Sun Oct 15 20:44:33 CST 2023
CPU: ARMv7 Processor [410fc090] revision 0 (ARMv7), cr=10c5387d
CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing instruction cache
OF: fdt: Machine model: V2P-CA9
Memory policy: Data cache writeback
Reserved memory: created DMA memory pool at 0x4c000000, size 8 MiB
OF: reserved mem: initialized node vram@4c000000, compatible id shared-dma-pool
OF: reserved mem: 0x4c000000..0x4c7fffff (8192 KiB) nomap non-reusable vram@4c000000
cma: Reserved 16 MiB at 0x7f000000
Zone ranges:
  Normal   [mem 0x0000000060000000-0x000000007fffffff]
Movable zone start for each node
Early memory node ranges
  node   0: [mem 0x0000000060000000-0x000000007fffffff]
Initmem setup node 0 [mem 0x0000000060000000-0x000000007fffffff]
CPU: All CPU(s) started in SVC mode.
percpu: Embedded 16 pages/cpu s34516 r8192 d22828 u65536
Kernel command line: root=/dev/mmcblk0 rw console=ttyAMA0
printk: log_buf_len individual max cpu contribution: 4096 bytes
printk: log_buf_len total cpu_extra contributions: 12288 bytes
printk: log_buf_len min size: 16384 bytes
printk: log_buf_len: 32768 bytes
printk: early log buf free: 14824(90%)
Dentry cache hash table entries: 65536 (order: 6, 262144 bytes, linear)
Inode-cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
Built 1 zonelists, mobility grouping on.  Total pages: 130048
mem auto-init: stack:off, heap alloc:off, heap free:off
Memory: 488696K/524288K available (9216K kernel code, 685K rwdata, 2052K rodata, 1024K init, 178K bss, 19208K reserved, 16384K cma-reserved)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
trace event string verifier disabled
rcu: Hierarchical RCU implementation.
rcu:    RCU event tracing is enabled.
rcu:    RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=4
NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
GIC CPU mask not found - kernel will fail to boot.
GIC CPU mask not found - kernel will fail to boot.
L2C: platform modifies aux control register: 0x02020000 -> 0x02420000
L2C: DT/platform modifies aux control register: 0x02020000 -> 0x02420000
L2C-310 enabling early BRESP for Cortex-A9
L2C-310 full line of zeros enabled for Cortex-A9
L2C-310 dynamic clock gating disabled, standby mode disabled
L2C-310 cache controller enabled, 8 ways, 128 kB
L2C-310: CACHE_ID 0x410000c8, AUX_CTRL 0x46420001
rcu: srcu_init: Setting srcu_struct sizes based on contention.
sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
clocksource: arm,sp804: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275 ns
smp_twd: clock not found -2
Console: colour dummy device 80x30
Calibrating local timer... 90.94MHz.
Calibrating delay loop... 489.06 BogoMIPS (lpj=2445312)
CPU: Testing write buffer coherency: ok
CPU0: Spectre v2: using BPIALL workaround
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Setting up static identity map for 0x60100000 - 0x60100060
rcu: Hierarchical SRCU implementation.
rcu:    Max phase no-delay instances is 1000.
smp: Bringing up secondary CPUs ...
smp: Brought up 1 node, 1 CPU
SMP: Total of 1 processors activated (489.06 BogoMIPS).
CPU: All CPU(s) started in SVC mode.
devtmpfs: initialized
VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 0
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
NET: Registered PF_NETLINK/PF_ROUTE protocol family
DMA: preallocated 256 KiB pool for atomic coherent allocations
cpuidle: using governor ladder
hw-breakpoint: debug architecture 0x4 unsupported.
Serial: AMBA PL011 UART driver
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
i2c 0-0039: Fixed dependency cycle(s) with /bus@40000000/motherboard-bus@40000000/iofpga@7,00000000/clcd@1f000/port/endpoint
i2c 0-0039: Fixed dependency cycle(s) with /clcd@10020000/port/endpoint
pps_core: LinuxPPS API ver. 1 registered
pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <[email protected]>
PTP clock support registered
Advanced Linux Sound Architecture Driver Initialized.
clocksource: Switched to clocksource arm,sp804
NET: Registered PF_INET protocol family
IP idents hash table entries: 8192 (order: 4, 65536 bytes, linear)
tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 4096 bytes, linear)
Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear)
TCP established hash table entries: 4096 (order: 2, 16384 bytes, linear)
TCP bind hash table entries: 4096 (order: 4, 65536 bytes, linear)
TCP: Hash tables configured (established 4096 bind 4096)
UDP hash table entries: 256 (order: 1, 8192 bytes, linear)
UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)
NET: Registered PF_UNIX/PF_LOCAL protocol family
RPC: Registered named UNIX socket transport module.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp-with-tls transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
hw perfevents: enabled with armv7_cortex_a9 PMU driver, 5 counters available
workingset: timestamp_bits=30 max_order=17 bucket_order=0
squashfs: version 4.0 (2009/01/31) Phillip Lougher
jffs2: version 2.2. (NAND) © 2001-2006 Red Hat, Inc.
9p: Installing v9fs 9p2000 file system support
io scheduler mq-deadline registered
io scheduler kyber registered
io scheduler bfq registered
OF: graph: no port node found in /bus@40000000/motherboard-bus@40000000/iofpga@7,00000000/i2c@16000/dvi-transmitter@60
sii902x 0-0060: supply iovcc not found, using dummy regulator
sii902x 0-0060: supply cvcc12 not found, using dummy regulator
simple-pm-bus bus@40000000:motherboard-bus@40000000:iofpga@7,00000000: Failed to create device link (0x180) with dcc:tcrefclk
simple-pm-bus bus@40000000:motherboard-bus@40000000:iofpga@7,00000000: Failed to create device link (0x180) with dcc:tcrefclk
physmap-flash 40000000.flash: physmap platform flash device: [mem 0x40000000-0x43ffffff]
40000000.flash: Found 2 x16 devices at 0x0 in 32-bit bank. Manufacturer ID 0x000000 Chip ID 0x000000
Intel/Sharp Extended Query Table at 0x0031
Using buffer write method
physmap-flash 40000000.flash: physmap platform flash device: [mem 0x44000000-0x47ffffff]
40000000.flash: Found 2 x16 devices at 0x0 in 32-bit bank. Manufacturer ID 0x000000 Chip ID 0x000000
Intel/Sharp Extended Query Table at 0x0031
Using buffer write method
Concatenating MTD devices:
(0): "40000000.flash"
(1): "40000000.flash"
into device "40000000.flash"
physmap-flash 48000000.psram: physmap platform flash device: [mem 0x48000000-0x49ffffff]
smsc911x 4e000000.ethernet eth0: MAC Address: 52:54:00:12:34:56
isp1760 4f000000.usb: isp1760 bus width: 32, oc: digital
isp1760 4f000000.usb: NXP ISP1760 USB Host Controller
isp1760 4f000000.usb: new USB bus registered, assigned bus number 1
isp1760 4f000000.usb: Scratch test failed. 0x00000000
isp1760 4f000000.usb: can't setup: -19
isp1760 4f000000.usb: USB bus 1 deregistered
usbcore: registered new interface driver usb-storage
rtc-pl031 10017000.rtc: registered as rtc0
rtc-pl031 10017000.rtc: setting system clock to 2023-10-25T13:07:54 UTC (1698239274)
mmci-pl18x 10005000.mmci: Got CD GPIO
mmci-pl18x 10005000.mmci: Got WP GPIO
mmci-pl18x 10005000.mmci: mmc0: PL181 manf 41 rev0 at 0x10005000 irq 35,36 (pio)
ledtrig-cpu: registered to indicate activity on CPUs
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
input: AT Raw Set 2 keyboard as /devices/platform/bus@40000000/bus@40000000:motherboard-bus@40000000/bus@40000000:motherboard-bus@40000000:iofpga@7,00000000/10006000.kmi/serio0/input/input0
mmc0: new SD card at address 4567
mmcblk0: mmc0:4567 QEMU! 32.0 MiB
aaci-pl041 10004000.aaci: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 37
aaci-pl041 10004000.aaci: FIFO 512 entries
NET: Registered PF_PACKET protocol family
9pnet: Installing 9P2000 support
Registering SWP/SWPB emulation handler
10009000.serial: ttyAMA0 at MMIO 0x10009000 (irq = 38, base_baud = 0) is a PL011 rev1
printk: console [ttyAMA0] enabled
1000a000.serial: ttyAMA1 at MMIO 0x1000a000 (irq = 39, base_baud = 0) is a PL011 rev1
1000b000.serial: ttyAMA2 at MMIO 0x1000b000 (irq = 40, base_baud = 0) is a PL011 rev1
1000c000.serial: ttyAMA3 at MMIO 0x1000c000 (irq = 41, base_baud = 0) is a PL011 rev1
drm-clcd-pl111 1001f000.clcd: assigned reserved memory node vram@4c000000
drm-clcd-pl111 1001f000.clcd: using device-specific reserved memory
drm-clcd-pl111 1001f000.clcd: core tile graphics present
drm-clcd-pl111 1001f000.clcd: this device will be deactivated
drm-clcd-pl111 1001f000.clcd: Versatile Express init failed - -19
drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111
drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111
clk: Disabling unused clocks
ALSA device list:
  #0: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 37
input: ImExPS/2 Generic Explorer Mouse as /devices/platform/bus@40000000/bus@40000000:motherboard-bus@40000000/bus@40000000:motherboard-bus@40000000:iofpga@7,00000000/10007000.kmi/serio1/input/input2
drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111
EXT4-fs (mmcblk0): mounting ext3 file system using the ext4 subsystem
EXT4-fs (mmcblk0): recovery complete
EXT4-fs (mmcblk0): mounted filesystem dee5646e-fd03-47fb-9a70-e1714f5b4c73 r/w with ordered data mode. Quota mode: disabled.
VFS: Mounted root (ext3 filesystem) on device 179:0.
Freeing unused kernel image (initmem) memory: 1024K
Run /sbin/init as init process
random: crng init done
mkdir: can't create directory '/dev/pts': File exists

Please press Enter to activate this console. drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111
amba 1000f000.wdt: deferred probe pending
amba 10020000.clcd: deferred probe pending
amba 100e0000.memory-controller: deferred probe pending
amba 100e1000.memory-controller: deferred probe pending
amba 100e5000.watchdog: deferred probe pending
i2c 0-0039: deferred probe pending

参考

• https://zhuanlan.zhihu.com/p/112128390