环境介绍
Win7 64 + Vmware 11 + ubuntu14.04 32
u-boot 版本：u-boot-2015-04
Linux kernel版本：linux-3.16.y
busybox版本：1_24_stable
交叉编译工具链：arm-linux-gnueabi-
qemu版本：stable-2.4
概述
这里我采用的方法是，利用网络引导的方式启动Linux内核。具体方式如下：
开启Qemu的网络支持功能，启动u-boot，设置u-boot的环境变量，u-boot采用tftp的方式将uImage格式的Linux内核下载到内存地址0x60003000处，为什么是0x60000000起始的地址，参考文件u-boot的配置文件 include/configs/vexpress_common.h。如果用Qemu直接启动Kernel，是通过-append parameter 的方式给kernel传参的，现在是通过u-boot，那么需要通过u-boot的环境变量bootargs，可以设置为如下值 setenv bootargs 'root=/dev/mmcblk0 console=ttyAMA0 console=tty0'。 然后设置u-boot环境变量bootcmd，如下: setenv bootcmd 'tftp 0x60003000 uImage; bootm 0x60003000'.
具体步骤
1、启动Qemu的网络支持
这个请参考博客：http://www.cnblogs.com/pengdonglin137/p/5023340.html
2、配置u-boot
主要是修改include/configs/vexpress_common.h
diff --git a/include/configs/vexpress_common.h b/include/configs/vexpress_common.h
index 0c1da01..9fa7d9e 100644
--- a/include/configs/vexpress_common.h
+++ b/include/configs/vexpress_common.h
@@ -48,6 +48,11 @@
#define CONFIG_SYS_TEXT_BASE 0x80800000
#endif
+/* netmask */
+#define CONFIG_IPADDR 192.168.11.5
+#define CONFIG_NETMASK 255.255.255.0
+#define CONFIG_SERVERIP 192.168.11.20
+
/*
* Physical addresses, offset from V2M_PA_CS0-3
*/
@@ -202,7 +207,9 @@
#define CONFIG_SYS_INIT_SP_ADDR CONFIG_SYS_GBL_DATA_OFFSET
/* Basic environment settings */
-#define CONFIG_BOOTCOMMAND "run bootflash;"
+/* #define CONFIG_BOOTCOMMAND "run bootflash;" */
+#define CONFIG_BOOTCOMMAND "tftp 0x60003000 uImage; setenv bootargs 'root=/dev/mmcblk0 console=ttyAMA0'; bootm 0x60003000
+
说明：
这里我把ipaddr等设置为了192.168.11.x网段，这个需要跟br0的网址一致，br0的地址在/etc/qemu-ifuo中修改：
#!/bin/sh
echo sudo tunctl -u $(id -un) -t $1
sudo tunctl -u $(id -un) -t $1
echo sudo ifconfig $1 0.0.0.0 promisc up
sudo ifconfig $1 0.0.0.0 promisc up
echo sudo brctl addif br0 $1
sudo brctl addif br0 $1
echo brctl show
brctl show
sudo ifconfig br0 192.168.11.20
然后重新编译u-boot代码
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j2
测试：
qemu-system-arm -M vexpress-a9 \
-kernel u-boot \
-nographic \
-m 512M \
-net nic,vlan=0 -net tap,vlan=0,ifname=tap0
运行：
U-Boot 2015.07-rc3-00092-gf3edfd3-dirty (Dec 05 2015 - 22:00:46 -0800)
DRAM: 512 MiB
WARNING: Caches not enabled
Flash: 128 MiB
MMC: MMC: 0
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Net: smc911x-0
Warning: smc911x-0 using MAC address from net device
Hit any key to stop autoboot: 0
VExpress# ping 192.168.11.20
smc911x: MAC 52:54:00:12:34:56
smc911x: detected LAN9118 controller
smc911x: phy initialized
smc911x: MAC 52:54:00:12:34:56
Using smc911x-0 device
smc911x: MAC 52:54:00:12:34:56
host 192.168.11.20 is alive
2、配置Linux Kernel
因为要用u-boot引导，所以需要把Kernel编译成uImage格式。
执行如下命令：
make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm O=./out_vexpress_3_16 uImage -j2
编译时会报错：
make[1]: Entering directory `/root/tq2440_work/kernel/linux-stable/out_vexpress_3_16'
CHK include/config/kernel.release
GEN ./Makefile
CHK include/generated/uapi/linux/version.h
Using .. as source for kernel
CHK include/generated/utsrelease.h
make[2]: `include/generated/mach-types.h' is up to date.
CALL ../scripts/checksyscalls.sh
CHK include/generated/compile.h
CHK kernel/config_data.h
Kernel: arch/arm/boot/Image is ready
Kernel: arch/arm/boot/zImage is ready
multiple (or no) load addresses:
This is incompatible with uImages
Specify LOADADDR on the commandline to build an uImage
make[2]: *** [arch/arm/boot/uImage] Error 1
make[1]: *** [uImage] Error 2
make: *** [sub-make] Error 2
这里需要我们制定LOADADDR的值，即uImage的加载地址，根据u-boot，我们可以将其设置为0x60003000.
修改后的命令如下：
make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm O=./out_vexpress_3_16 LOADADDR=0x60003000 uImage -j2
编译信息：
make[1]: Entering directory `/root/tq2440_work/kernel/linux-stable/out_vexpress_3_16'
CHK include/config/kernel.release
GEN ./Makefile
CHK include/generated/uapi/linux/version.h
Using .. as source for kernel
CHK include/generated/utsrelease.h
make[2]: `include/generated/mach-types.h' is up to date.
CALL ../scripts/checksyscalls.sh
CHK include/generated/compile.h
CHK kernel/config_data.h
Kernel: arch/arm/boot/Image is ready
Kernel: arch/arm/boot/zImage is ready
UIMAGE arch/arm/boot/uImage
Image Name: Linux-3.16.7
Created: Sat Dec 5 23:10:41 2015
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 3326696 Bytes = 3248.73 kB = 3.17 MB
Load Address: 0x60003000
Entry Point: 0x60003000
Image arch/arm/boot/uImage is ready
编译生成的uImage在 linux-stable/out_vexpress_3_16/arch/arm/boot下，然后将uImage拷贝到/tftpboot目录下，关于tftp服务器的配置请参考：
3、测试
执行如下命令：
qemu-system-arm -M vexpress-a9 \
-kernel /root/tq2440_work/u-boot/u-boot/u-boot \
-nographic \
-m 512M \
-net nic,vlan=0 -net tap,vlan=0,ifname=tap0 \
-sd /root/tq2440_work/busybox_study/a9rootfs.ext3
启动信息：
sudo tunctl -u root -t tap0
sudo ifconfig tap0 0.0.0.0 promisc up
sudo brctl addif br0 tap0
brctl show
bridge name bridge id STP enabled interfaces
br0 8000.000c290bd2f3 no eth0
tap0
U-Boot 2015.07-rc3-00092-gf3edfd3-dirty (Dec 05 2015 - 23:20:40 -0800)
DRAM: 512 MiB
WARNING: Caches not enabled
Flash: 128 MiB
MMC: MMC: 0
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Net: smc911x-0
Warning: smc911x-0 using MAC address from net device
Hit any key to stop autoboot: 0
smc911x: MAC 52:54:00:12:34:56
smc911x: detected LAN9118 controller
smc911x: phy initialized
smc911x: MAC 52:54:00:12:34:56
Using smc911x-0 device
TFTP from server 192.168.11.20; our IP address is 192.168.11.5
Filename 'uImage'.
Load address: 0x60003000
Loading: #################################################################
#################################################################
#################################################################
################################
796.9 KiB/s
done
Bytes transferred = 3326760 (32c328 hex)
smc911x: MAC 52:54:00:12:34:56
## Booting kernel from Legacy Image at 60003000 ...
Image Name: Linux-3.16.7
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 3326696 Bytes = 3.2 MiB
Load Address: 60003000
Entry Point: 60003000
Verifying Checksum ... OK
Loading Kernel Image ... OK
Starting kernel ...
Booting Linux on physical CPU 0x0
Initializing cgroup subsys cpuset
Linux version 3.16.7 (root@ubuntu) (gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-12ubuntu1) ) #5 SMP Sat Dec 5 21:17:17 PST 2015
CPU: ARMv7 Processor [410fc090] revision 0 (ARMv7), cr=10c53c7d
CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing instruction cache
Machine: ARM-Versatile Express
Memory policy: Data cache writeback
CPU: All CPU(s) started in SVC mode.
sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 178956969942ns
PERCPU: Embedded 7 pages/cpu @9fbed000 s7552 r8192 d12928 u32768
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 130048
Kernel command line: root=/dev/mmcblk0 console=ttyAMA0
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)
Memory: 513272K/524288K available (4563K kernel code, 190K rwdata, 1292K rodata, 239K init, 149K bss, 11016K reserved)
Virtual kernel memory layout:
vector : 0xffff0000 - 0xffff1000 ( 4 kB)
fixmap : 0xffc00000 - 0xffe00000 (2048 kB)
vmalloc : 0xa0800000 - 0xff000000 (1512 MB)
lowmem : 0x80000000 - 0xa0000000 ( 512 MB)
modules : 0x7f000000 - 0x80000000 ( 16 MB)
.text : 0x80008000 - 0x805c01b0 (5857 kB)
.init : 0x805c1000 - 0x805fcd80 ( 240 kB)
.data : 0x805fe000 - 0x8062dba0 ( 191 kB)
.bss : 0x8062dba8 - 0x8065336c ( 150 kB)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Hierarchical RCU implementation.
RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
NR_IRQS:16 nr_irqs:16 16
GIC CPU mask not found - kernel will fail to boot.
GIC CPU mask not found - kernel will fail to boot.
smp_twd: clock not found -2
Console: colour dummy device 80x30
Calibrating local timer... 88.21MHz.
Calibrating delay loop... 310.68 BogoMIPS (lpj=1553408)
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
missing device node for CPU 0
CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Setting up static identity map for 0x604546d0 - 0x60454728
Brought up 1 CPUs
SMP: Total of 1 processors activated.
CPU: All CPU(s) started in SVC mode.
devtmpfs: initialized
VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 0
regulator-dummy: no parameters
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
cpuidle: using governor ladder
cpuidle: using governor menu
hw-breakpoint: debug architecture 0x4 unsupported.
Serial: AMBA PL011 UART driver
mb:uart0: ttyAMA0 at MMIO 0x10009000 (irq = 37, base_baud = 0) is a PL011 rev1
console [ttyAMA0] enabled
mb:uart1: ttyAMA1 at MMIO 0x1000a000 (irq = 38, base_baud = 0) is a PL011 rev1
mb:uart2: ttyAMA2 at MMIO 0x1000b000 (irq = 39, base_baud = 0) is a PL011 rev1
mb:uart3: ttyAMA3 at MMIO 0x1000c000 (irq = 40, base_baud = 0) is a PL011 rev1
fixed-dummy: no parameters
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.
Switched to clocksource v2m-timer1
NET: Registered protocol family 2
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)
TCP: reno registered
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.
CPU PMU: probing PMU on CPU 0
hw perfevents: enabled with ARMv7 Cortex-A9 PMU driver, 1 counters available
futex hash table entries: 256 (order: 2, 16384 bytes)
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
msgmni has been set to 1002
io scheduler noop registered (default)
clcd-pl11x ct:clcd: PL111 rev2 at 0x10020000
clcd-pl11x ct:clcd: CT-CA9X4 hardware, XVGA display
Console: switching to colour frame buffer device 128x48
physmap platform flash device: 04000000 at 40000000
physmap-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 platform flash device: 04000000 at 44000000
physmap-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): "physmap-flash"
(1): "physmap-flash"
into device "physmap-flash"
libphy: smsc911x-mdio: probed
smsc911x smsc911x eth0: attached PHY driver [Generic PHY] (mii_bus:phy_addr=smsc911x-fffffff:01, irq=-1)
smsc911x smsc911x eth0: MAC Address: 52:54:00:12:34:56
isp1760 isp1760: NXP ISP1760 USB Host Controller
isp1760 isp1760: new USB bus registered, assigned bus number 1
isp1760 isp1760: Scratch test failed.
isp1760 isp1760: can't setup: -19
isp1760 isp1760: USB bus 1 deregistered
isp1760: Failed to register the HCD device
usbcore: registered new interface driver usb-storage
mousedev: PS/2 mouse device common for all mice
rtc-pl031 mb:rtc: rtc core: registered pl031 as rtc0
mmci-pl18x mb:mmci: mmc0: PL181 manf 41 rev0 at 0x10005000 irq 41,42 (pio)
input: AT Raw Set 2 keyboard as /devices/mb:kmi0/serio0/input/input0
ledtrig-cpu: registered to indicate activity on CPUs
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 SD card at address 4567
mmcblk0: mmc0:4567 QEMU! 32.0 MiB
mmcblk0: unknown partition table
aaci-pl041 mb:aaci: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 43
aaci-pl041 mb:aaci: FIFO 512 entries
oprofile: using arm/armv7-ca9
TCP: cubic registered
NET: Registered protocol family 17
9pnet: Installing 9P2000 support
rtc-pl031 mb:rtc: setting system clock to 2015-12-06 07:22:11 UTC (1449386531)
ALSA device list:
#0: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 43
input: ImExPS/2 Generic Explorer Mouse as /devices/mb:kmi1/serio1/input/input2
kjournald starting. Commit interval 5 seconds
EXT3-fs (mmcblk0): using internal journal
EXT3-fs (mmcblk0): recovery complete
EXT3-fs (mmcblk0): mounted filesystem with writeback data mode
VFS: Mounted root (ext3 filesystem) on device 179:0.
Freeing unused kernel memory: 236K (805c1000 - 805fc000)
random: nonblocking pool is initialized
mount: mounting none on /proc/bus/usb failed: No such file or directory
Please press Enter to activate this console.
[root@vexpress ]#
[root@vexpress ]#
[root@vexpress ]#
[root@vexpress ]#
[root@vexpress ]#
[root@vexpress ]# ls
bin etc linuxrc mnt root sys usr
dev lib lost+found proc sbin tmp var
[root@vexpress ]# ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
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)
[root@vexpress ]# ifconfig eth0 192.168.11.5
smsc911x smsc911x eth0: SMSC911x/921x identified at 0xa0a40000, IRQ: 47
[root@vexpress ]# ping 192.168.11.20
PING 192.168.11.20 (192.168.11.20): 56 data bytes
64 bytes from 192.168.11.20: seq=0 ttl=64 time=20.928 ms
64 bytes from 192.168.11.20: seq=1 ttl=64 time=1.250 ms
64 bytes from 192.168.11.20: seq=2 ttl=64 time=0.573 ms
^C
--- 192.168.11.20 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.573/7.583/20.928 ms
[root@vexpress ]#
可以在/etc/init.d/rcS中设置eth0的ip地址为 ifconfig eth0 192.168.11.5
4、开启图形界面
修改u-boot的bootargs环境变量为：
setenv bootargs 'root=/dev/mmcblk0 console=ttyAMA0 console=tty0';
执行命令：
qemu-system-arm -M vexpress-a9 \
-kernel /root/tq2440_work/u-boot/u-boot/u-boot \
-nographic \
-m 512M \
-net nic,vlan=0 -net tap,vlan=0,ifname=tap0 \
-sd /root/tq2440_work/busybox_study/a9rootfs.ext3
截图：
未完待续。
