USB無線網卡的Linux驅動移植

⑥ 將安裝目錄下的iwconfig、iwlist等下載到目標板。主要使用的命令及功能：

◆ iwconfig，回車，查看所有無線網卡;

◆ iwconfig wlan0，查看wlan0;

◆ iwconfig wlan0 essid xx，配置網卡SSID為xx;

◆ iwlist wlan0 scan|grep ESSID，搜索周邊所有無線網卡的ESSID。

2.6　無線網卡測試

(1) 插入無線網卡，自動安裝USB host驅動

[root@(none) tmp]# uname a

Linux(none) 2.6.12h1940 #59 Tue May 3 13:12:53 CST 2011 armv4tl unknown

[root@(none) tmp]# usb 11:new full speed USB device using s3c2410ohci and address 4

usb 11: Product: RTL8188S WLAN Adapter

usb 11: Manufacturer: Manufacturer Realtek

usb 11: SerialNumber: 00e04c000001

(2) 加載模塊8712u.ko

insmod 8712u.ko

(3) 喚醒USB無線網卡驅動

ifconfig wlan0 up

(4) 搜索周邊無線網絡

[root@(none) tmp]# iwlist wlan0 scan | grep ESSID

fwdbg: get survey cmd

fwdbg: survey done (00000005, 00000000)

ESSID: TPLINK_WSW

ESSID: TPLINK_717E24

ESSID: dlink

ESSID: newnav

ESSID: dgdz

(5) 配置wlan0的SSID

iwconfig wlan essid TPLINK_717E24

配置成功后利用iwconfig回顯：

[root@(none) tmp]# uname a

Linux (none) 2.6.12h1940 #59 Tue May 3 13:12:53 CST 2011 armv4tl unknown

[root@(none) tmp]# iwconfig wlan0

wlan0IEEE 802.11bg ESSID:TPLINK_717E24

Mode: Managed Frequency: 2.437 GHz Access Point: 00:25:86:71:7E:24

Bit Rate: 54 Mb/s

Encryption key:off

Power Management: off

Link Quality=52/100 Signal level=52/100 Noise level=0/100

Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0

Tx excessive retries:0 Invalid misc:0 Missed beacon:0

(6) IP動態分配

自動申請動態IP：

udhcpc i wlan0

顯示如下信息：

[root@(none) tmp]# uname a

Linux (none) 2.6.12h1940 #59 Tue May 3 13:12:53 CST 2011 armv4tl unknown

[root@(none) tmp]# udhcpc i wlan0

udhcpc (v0.9.9pre) started

udhcpc[490]: udhcpc (v0.9.9pre) started

Sending discover...

udhcpc[490]: Sending discover...

Sending select for 172.16.51.9...

udhcpc[490]: Sending select for 172.16.51.9...

Lease of 172.16.51.9 obtained, lease time 691200

udhcpc[490]: Lease of 172.16.51.9 obtained, lease time 691200

deleting routers

route: SIOC[ADD|DEL]RT: No such process

adding dns 61.153.216.99

adding dns 61.153.216.104

運行ifconfig命令后，顯示最終配置：

[root@(none) tmp]# uname a

Linux (none) 2.6.12h1940 #59 Tue May 3 13:12:53 CST 2011 armv4tl unknown

[root@(none) tmp]# ifconfig wlan0

wlan0 Line encap: Ethernet HWaddr 00:0F:10:54:0E:1B

inet addr: 172.16.51.9 Bcast:172.16.255.255 Mask: 255.255 Mask:255.255.255.0

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:618 errors:0 dropped:0 overruns:0 frame:0

TX packets:2 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

(7) ping測試

ping測試時需要加c參數控制ping次數，否則會一直不停測試，并且無法kill。

[root@(none) tmp]# ping c 2 172.16.51.9

PING 172.16.51.9 (172.16.51.9): 56 data bytes

64 bytes from 172.16.51.9: icmp_seq=0 ttl=64 time=1.4 ms

64 bytes from 172.16.51.9: icmp_seq=1 ttl=64 time=0.7 ms

---172.16.51.9 ping statistics 勃勃

2 packets transmitted, 2 packets received, 0% packet loss

roundtrip min/avg/max=0.7/1.0/1.4 ms

3　討論

在USB無線網卡驅動移植過程中，將主要的文件netdevice.h、wireless.h、iw_handler.h、dev.c等進行替換后，內核已經能編譯成功。將內核下載并重啟開發板后，加載驅動成功，并能利用iwlist搜索到周邊的WLAN網絡。在利用iwconfig給驅動指定SSID時iwconfig引起內核崩潰。初判原因不應為wirelesstools程序。加入ip.h、icmp.h socket.h等文件后iwconfig指定SSID成功。最后進行ping測試時，出現ping 127.1和本機IP均失敗的情況。使用strace跟蹤ping執行過程，發現recvfrom()函數參數傳遞錯誤，替換neighbour.c af_netlink.c等文件后ping 127.1成功。

若系統內核升級到Linux 2.6.30，驅動能編譯通過，但只要一發出ifconfig命令，內核即崩潰。即使高版本內核在移植時也有問題，這些問題需要進一步研究。