下载内核源码

下载内核有两种方法，一种是用git直接下载内核代码树，方便后面的内核开发。另一种是直接到内核社区下载稳定版本（详见：https://www.kernel.org/pub/linux/kernel/v4.x/）。下面演示从Linux kernel主线下载代码进行编译。

git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

安装arm的交叉编译工具链

因为交叉编译容易出现兼容性问题，所以最好使用稳定的版本，这里使用4.8版本：

QQ图片20180516110424.png

编译Linux内核

生成vexpress开发板子的config文件：

make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm vexpress_defconfig

编译：

make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm

生成的内核镱像位于arch/arm/boot/zImage， 后续qemu启动时需要使用该镜像。

下载和安装qemu模拟器

wget http://wiki.qemu-project.org/download/qemu-2.5.0.tar.bz2

配置qemu，支持模拟arm架构下的所有单板：

./configure --target-list=arm-softmmu --audio-drv-list=

编译和安装：

make
make install

测试qemu和内核启动

qemu已经安装好，内核也编译成功之后，到这里最好是测试一下
运行命令很简单：

qemu-system-arm -M vexpress-a9 -m 512M -kernel ./arch/arm/boot/zImage -dtb  ./arch/arm/boot/dts/vexpress-v2p-ca9.dtb -nographic -append "console=ttyAMA0"

这里简单介绍下qemu命令的参数：

• -M vexpress-a9 模拟vexpress-a9单板，你可以使用-M ?参数来获取该qemu版本支持的所有单板

• -m 512M 单板运行物理内存512M

• -kernel ./arch/arm/boot/zImage 告诉qemu单板运行内核镜像路径

• -nographic 不使用图形化界面，只使用串口

• -append "console=ttyAMA0" 内核启动参数，这里告诉内核vexpress单板运行，串口设备是那个tty。

执行测试命令qemu-system-arm -M vexpress-a9 -m 512M -kernel ./arch/arm/boot/zImage -dtb ./arch/arm/boot/dts/vexpress-v2p-ca9.dtb -nographic -append "console=ttyAMA0"， 则启动内核，打印出内核启动信息，如下：

pulseaudio: set_sink_input_volume() failed
pulseaudio: Reason: Invalid argument
pulseaudio: set_sink_input_mute() failed
pulseaudio: Reason: Invalid argument
Booting Linux on physical CPU 0x0
Linux version 4.16.2 (hades@hades) (gcc version 4.8.4 (GCC)) #3 SMP Wed May 16 10:49:42 CST 2018
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
CPU: All CPU(s) started in SVC mode.
random: get_random_bytes called from start_kernel+0x88/0x3ec with crng_init=0
percpu: Embedded 16 pages/cpu @(ptrval) s36288 r8192 d21056 u65536
Built 1 zonelists, mobility grouping on.  Total pages: 130048
Kernel command line: console=ttyAMA0
log_buf_len individual max cpu contribution: 4096 bytes
log_buf_len total cpu_extra contributions: 12288 bytes
log_buf_len min size: 16384 bytes
log_buf_len: 32768 bytes
early log buf free: 15056(91%)
Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
Memory: 509624K/524288K available (6144K kernel code, 390K rwdata, 1372K rodata, 1024K init, 164K bss, 14664K reserved, 0K cma-reserved)
Virtual kernel memory layout:
    vector  : 0xffff0000 - 0xffff1000   (   4 kB)
    fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
    vmalloc : 0xa0800000 - 0xff800000   (1520 MB)
    lowmem  : 0x80000000 - 0xa0000000   ( 512 MB)
    modules : 0x7f000000 - 0x80000000   (  16 MB)
      .text : 0x(ptrval) - 0x(ptrval)   (7136 kB)
      .init : 0x(ptrval) - 0x(ptrval)   (1024 kB)
      .data : 0x(ptrval) - 0x(ptrval)   ( 391 kB)
       .bss : 0x(ptrval) - 0x(ptrval)   ( 165 kB)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
Hierarchical RCU implementation.
    RCU event tracing is enabled.
    RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
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
smp_twd: clock not found -2
sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
clocksource: arm,sp804: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275 ns
Failed to initialize '/smb@4000000/motherboard/iofpga@7,00000000/timer@12000': -22
Console: colour dummy device 80x30
Calibrating local timer... 99.42MHz.
Calibrating delay loop... 743.83 BogoMIPS (lpj=3719168)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
CPU: Testing write buffer coherency: ok
CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Setting up static identity map for 0x60100000 - 0x60100060
Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
smp: Brought up 1 node, 1 CPU
SMP: Total of 1 processors activated (743.83 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)
random: fast init done
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
cpuidle: using governor ladder
hw-breakpoint: debug architecture 0x4 unsupported.
Serial: AMBA PL011 UART driver
OF: amba_device_add() failed (-19) for /memory-controller@100e0000
OF: amba_device_add() failed (-19) for /memory-controller@100e1000
OF: amba_device_add() failed (-19) for /watchdog@100e5000
irq: type mismatch, failed to map hwirq-75 for interrupt-controller@1e001000!
10009000.uart: ttyAMA0 at MMIO 0x10009000 (irq = 38, base_baud = 0) is a PL011 rev1
console [ttyAMA0] enabled
1000a000.uart: ttyAMA1 at MMIO 0x1000a000 (irq = 39, base_baud = 0) is a PL011 rev1
1000b000.uart: ttyAMA2 at MMIO 0x1000b000 (irq = 40, base_baud = 0) is a PL011 rev1
1000c000.uart: ttyAMA3 at MMIO 0x1000c000 (irq = 41, base_baud = 0) is a PL011 rev1
OF: amba_device_add() failed (-19) for /smb@4000000/motherboard/iofpga@7,00000000/wdt@f000
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Advanced Linux Sound Architecture Driver Initialized.
clocksource: Switched to clocksource arm,sp804
NET: Registered protocol family 2
tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes)
TCP established hash table entries: 4096 (order: 2, 16384 bytes)
TCP bind hash table entries: 4096 (order: 3, 32768 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
UDP hash table entries: 256 (order: 1, 8192 bytes)
UDP-Lite hash table entries: 256 (order: 1, 8192 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.
hw perfevents: enabled with armv7_cortex_a9 PMU driver, 1 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 noop registered (default)
io scheduler mq-deadline registered
io scheduler kyber registered
clcd-pl11x 10020000.clcd: PL111 designer 41 rev2 at 0x10020000
clcd-pl11x 10020000.clcd: clcd@10020000 hardware, 1024x768@59 display
Console: switching to colour frame buffer device 128x48
clcd-pl11x 1001f000.clcd: PL111 designer 41 rev2 at 0x1001f000
clcd-pl11x 1001f000.clcd: clcd@1f000 hardware, 640x480@59 display
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
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"
libphy: Fixed MDIO Bus: probed
libphy: smsc911x-mdio: probed
smsc911x 4e000000.ethernet eth0: MAC Address: 52:54:00:12:34:56
isp1760 4f000000.usb: 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.
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: rtc core: registered pl031 as rtc0
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 34,35 (pio)
ledtrig-cpu: registered to indicate activity on CPUs
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
aaci-pl041 10004000.aaci: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 33
aaci-pl041 10004000.aaci: FIFO 512 entries
oprofile: using arm/armv7-ca9
NET: Registered protocol family 17
9pnet: Installing 9P2000 support
Registering SWP/SWPB emulation handler
input: AT Raw Set 2 keyboard as /devices/platform/smb@4000000/smb@4000000:motherboard/smb@4000000:motherboard:iofpga@7,00000000/10006000.kmi/serio0/input/input0
rtc-pl031 10017000.rtc: setting system clock to 2018-05-16 02:57:41 UTC (1526439461)
ALSA device list:
  #0: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 33
input: ImExPS/2 Generic Explorer Mouse as /devices/platform/smb@4000000/smb@4000000:motherboard/smb@4000000:motherboard:iofpga@7,00000000/10007000.kmi/serio1/input/input2
VFS: Cannot open root device "(null)" or unknown-block(0,0): error -6
Please append a correct "root=" boot option; here are the available partitions:
1f00          131072 mtdblock0 
 (driver?)
1f01           32768 mtdblock1 
 (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.2 #3
Hardware name: ARM-Versatile Express
[<8010f820>] (unwind_backtrace) from [<8010c0f8>] (show_stack+0x10/0x14)
[<8010c0f8>] (show_stack) from [<8065ee0c>] (dump_stack+0x90/0xa4)
[<8065ee0c>] (dump_stack) from [<8011ebc4>] (panic+0xf0/0x264)
[<8011ebc4>] (panic) from [<8090128c>] (mount_block_root+0x1e4/0x2c8)
[<8090128c>] (mount_block_root) from [<80901490>] (mount_root+0x120/0x128)
[<80901490>] (mount_root) from [<809015f0>] (prepare_namespace+0x158/0x1a0)
[<809015f0>] (prepare_namespace) from [<80900f04>] (kernel_init_freeable+0x254/0x264)
[<80900f04>] (kernel_init_freeable) from [<80672a14>] (kernel_init+0x8/0x118)
[<80672a14>] (kernel_init) from [<801010e8>] (ret_from_fork+0x14/0x2c)
Exception stack(0x9f48ffb0 to 0x9f48fff8)
ffa0:                                     00000000 00000000 00000000 00000000
ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ffe0: 00000000 00000000 00000000 00000000 00000013 00000000
---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

最后kernel panic 没有根文件系统！

下载、编译和安装busybox

wget http://www.busybox.net/downloads/busybox-1.28.3.tar.bz2
cd busybox-1.28.3
make defconfig ARCH=arm
make CROSS_COMPILE=arm-linux- ARCH=arm
make install CROSS_COMPILE=arm-linux-  ARCH=arm

安装完成后，会在busybox目录下生成_install目录，该目录下的程序就是单板运行所需要的命令。

QQ图片20180516112822.png

查找没有MTD_FILE_MODE_RAW定义，可找到枚举定义：

/*
  * Read/write file modes for access to MTD
  */
 enum mtd_file_modes {
         MTD_MODE_NORMAL = MTD_OTP_OFF,
         MTD_MODE_OTP_FACTORY = MTD_OTP_FACTORY,
         MTD_MODE_OTP_USER = MTD_OTP_USER,
         MTD_MODE_RAW,
 };

修改busybox nandwrite.c:147 ，将 MTD_FILE_MODE_RAW替换成‘MTD_MODE_RAW

制作根文件系统目录结构

先在Ubuntu主机环境下，形成目录结构，里面存放的文件和目录与单板上运行所需要的目录结构完全一样，然后再打包成镜像，这个临时的目录结构称为根目录

创建rootfs目录（根目录），根文件系统内的文件全部放到这里

mkdir -p rootfs/{dev,etc/init.d,lib}

拷贝busybox命令到根目录下

sudo cp busybox-1.28.3/_install/* -r rootfs/ 

从交叉编译工具链中拷贝运行库到lib目录下

sudo cp -P /usr/local/arm_linux_4.8/lib/* rootfs/lib/ 

创建4个tty端终设备

sudo mknod rootfs/dev/tty1 c 4 1
sudo mknod rootfs/dev/tty2 c 4 2
sudo mknod rootfs/dev/tty3 c 4 3
sudo mknod rootfs/dev/tty4 c 4 4

制作根文件系统镜像

生成32M大小的镜像

 dd if=/dev/zero of=a9rootfs.ext4 bs=1M count=32

格式化成ext4文件系统

mkfs.ext4 a9rootfs.ext4

将文件拷贝到镜像中

sudo mkdir tmpfs
sudo mount -t ext4 a9rootfs.ext4 tmpfs/ -o loop
sudo cp -r rootfs/*  tmpfs/
sudo umount tmpfs

系统启动运行

完成上述所有步骤之后，就可以启动qemu来模拟vexpress开发板了，命令参数如下：

qemu-system-arm -M vexpress-a9 -m 512M -kernel ./linux-4.16.2/arch/arm/boot/zImage -dtb  ./linux-4.16.2/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -nographic -append "root=/dev/mmcblk0" console=ttyAMA0" -sd a9rootfs.ext4

内核启动打印出启动信息，到命令行提示符出现，则模拟成功

WARNING: Image format was not specified for 'a9rootfs.ext4' 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.
pulseaudio: set_sink_input_volume() failed
pulseaudio: Reason: Invalid argument
pulseaudio: set_sink_input_mute() failed
pulseaudio: Reason: Invalid argument
Booting Linux on physical CPU 0x0
Linux version 4.16.2 (hades@hades) (gcc version 4.8.4 (GCC)) #3 SMP Wed May 16 10:49:42 CST 2018
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
CPU: All CPU(s) started in SVC mode.
random: get_random_bytes called from start_kernel+0x88/0x3ec with crng_init=0
percpu: Embedded 16 pages/cpu @(ptrval) s36288 r8192 d21056 u65536
Built 1 zonelists, mobility grouping on.  Total pages: 130048
Kernel command line: root=/dev/mmcblk0 console=ttyAMA0
log_buf_len individual max cpu contribution: 4096 bytes
log_buf_len total cpu_extra contributions: 12288 bytes
log_buf_len min size: 16384 bytes
log_buf_len: 32768 bytes
early log buf free: 15036(91%)
Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
Memory: 509624K/524288K available (6144K kernel code, 390K rwdata, 1372K rodata, 1024K init, 164K bss, 14664K reserved, 0K cma-reserved)
Virtual kernel memory layout:
    vector  : 0xffff0000 - 0xffff1000   (   4 kB)
    fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
    vmalloc : 0xa0800000 - 0xff800000   (1520 MB)
    lowmem  : 0x80000000 - 0xa0000000   ( 512 MB)
    modules : 0x7f000000 - 0x80000000   (  16 MB)
      .text : 0x(ptrval) - 0x(ptrval)   (7136 kB)
      .init : 0x(ptrval) - 0x(ptrval)   (1024 kB)
      .data : 0x(ptrval) - 0x(ptrval)   ( 391 kB)
       .bss : 0x(ptrval) - 0x(ptrval)   ( 165 kB)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
Hierarchical RCU implementation.
    RCU event tracing is enabled.
    RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
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
smp_twd: clock not found -2
sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
clocksource: arm,sp804: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275 ns
Failed to initialize '/smb@4000000/motherboard/iofpga@7,00000000/timer@12000': -22
Console: colour dummy device 80x30
Calibrating local timer... 97.82MHz.
Calibrating delay loop... 755.30 BogoMIPS (lpj=3776512)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
CPU: Testing write buffer coherency: ok
CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Setting up static identity map for 0x60100000 - 0x60100060
Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
smp: Brought up 1 node, 1 CPU
SMP: Total of 1 processors activated (755.30 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)
random: fast init done
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
cpuidle: using governor ladder
hw-breakpoint: debug architecture 0x4 unsupported.
Serial: AMBA PL011 UART driver
OF: amba_device_add() failed (-19) for /memory-controller@100e0000
OF: amba_device_add() failed (-19) for /memory-controller@100e1000
OF: amba_device_add() failed (-19) for /watchdog@100e5000
irq: type mismatch, failed to map hwirq-75 for interrupt-controller@1e001000!
10009000.uart: ttyAMA0 at MMIO 0x10009000 (irq = 38, base_baud = 0) is a PL011 rev1
console [ttyAMA0] enabled
1000a000.uart: ttyAMA1 at MMIO 0x1000a000 (irq = 39, base_baud = 0) is a PL011 rev1
1000b000.uart: ttyAMA2 at MMIO 0x1000b000 (irq = 40, base_baud = 0) is a PL011 rev1
1000c000.uart: ttyAMA3 at MMIO 0x1000c000 (irq = 41, base_baud = 0) is a PL011 rev1
OF: amba_device_add() failed (-19) for /smb@4000000/motherboard/iofpga@7,00000000/wdt@f000
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Advanced Linux Sound Architecture Driver Initialized.
clocksource: Switched to clocksource arm,sp804
NET: Registered protocol family 2
tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes)
TCP established hash table entries: 4096 (order: 2, 16384 bytes)
TCP bind hash table entries: 4096 (order: 3, 32768 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
UDP hash table entries: 256 (order: 1, 8192 bytes)
UDP-Lite hash table entries: 256 (order: 1, 8192 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.
hw perfevents: enabled with armv7_cortex_a9 PMU driver, 1 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 noop registered (default)
io scheduler mq-deadline registered
io scheduler kyber registered
clcd-pl11x 10020000.clcd: PL111 designer 41 rev2 at 0x10020000
clcd-pl11x 10020000.clcd: clcd@10020000 hardware, 1024x768@59 display
Console: switching to colour frame buffer device 128x48
clcd-pl11x 1001f000.clcd: PL111 designer 41 rev2 at 0x1001f000
clcd-pl11x 1001f000.clcd: clcd@1f000 hardware, 640x480@59 display
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
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"
libphy: Fixed MDIO Bus: probed
libphy: smsc911x-mdio: probed
smsc911x 4e000000.ethernet eth0: MAC Address: 52:54:00:12:34:56
isp1760 4f000000.usb: 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.
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: rtc core: registered pl031 as rtc0
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 34,35 (pio)
ledtrig-cpu: registered to indicate activity on CPUs
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
aaci-pl041 10004000.aaci: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 33
aaci-pl041 10004000.aaci: FIFO 512 entries
oprofile: using arm/armv7-ca9
NET: Registered protocol family 17
9pnet: Installing 9P2000 support
Registering SWP/SWPB emulation handler
input: AT Raw Set 2 keyboard as /devices/platform/smb@4000000/smb@4000000:motherboard/smb@4000000:motherboard:iofpga@7,00000000/10006000.kmi/serio0/input/input0
mmc0: new SD card at address 4567
mmcblk0: mmc0:4567 QEMU! 32.0 MiB 
rtc-pl031 10017000.rtc: setting system clock to 2018-05-16 04:16:58 UTC (1526444218)
ALSA device list:
  #0: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 33
input: ImExPS/2 Generic Explorer Mouse as /devices/platform/smb@4000000/smb@4000000:motherboard/smb@4000000:motherboard:iofpga@7,00000000/10007000.kmi/serio1/input/input2
EXT4-fs (mmcblk0): couldn't mount as ext3 due to feature incompatibilities
EXT4-fs (mmcblk0): mounted filesystem with ordered data mode. Opts: (null)
VFS: Mounted root (ext4 filesystem) readonly on device 179:0.
Freeing unused kernel memory: 1024K
random: crng init done
can't run '/etc/init.d/rcS': No such file or directory

Please press Enter to activate this console. 
/ # ls
bin         etc         linuxrc     sbin
dev         lib         lost+found  usr
/ #