编译网上下载的开源软件opencapwap，使用make命令成功编译
但是默认的编译器是gcc，而我需要交叉编译，需要编译出能在MIPS下运行的程序。
编译结果如下（输出信息不多，全拷贝出来）：
[root@SS-SERVER1 capwap-0.93.3]# make all
/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/bin/mipsel-linux-gcc  -Wall -g -O0 -D_REENTRANT -DBCM -I /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/include  -DCW_DEBUGGING   -c -o CWThread.o CWThread.c
CWThread.c: In function `CWThreadTimedSemWait':
CWThread.c:466: warning: implicit declaration of function `sem_timedwait'/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/bin/mipsel-linux-gcc  -Wall -g -O0 -D_REENTRANT -DBCM -I /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/include  -DCW_DEBUGGING   -c -o CWBinding.o CWBinding.c
/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/bin/mipsel-linux-gcc  -Wall -g -O0 -D_REENTRANT -DBCM -I /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/include  -DCW_DEBUGGING   -c -o WTPBinding.o WTPBinding.c
/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/bin/mipsel-linux-gcc  -Wall -g -O0 -D_REENTRANT -DBCM -I /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/include  -DCW_DEBUGGING   -c -o WTPBcmDriverInteraction.o WTPBcmDriverInteraction.c
/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/bin/mipsel-linux-gcc  -Wall -g -O0 -D_REENTRANT -DBCM -I /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/include  -DCW_DEBUGGING   -c -o WTPSettingsFile.o WTPSettingsFile.c
/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/bin/mipsel-linux-gcc  -Wall -g -O0 -D_REENTRANT -DBCM -I /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/include  -DCW_DEBUGGING   -c -o timerlib.o timerlib.c
/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/bin/mipsel-linux-gcc  -DWRITE_STD_OUTPUT WTP.o WTPBcmFrameReceive.o WTPConfigFile.o WTPProtocol.o WTPProtocol_User.o WTPDiscoveryState.o WTPJoinState.o WTPConfigureState.o WTPDataCheckState.o WTPRunState.o WTPRunStateCheck.o WTPRetransmission.o WTPSulkingState.o CWCommon.o CWConfigFile.o CWErrorHandling.o CWSafeList.o CWList.o CWLog.o CWNetwork.o CWProtocol.o CWRandom.o CWSecurity.o CWOpenSSLBio.o CWStevens.o CWThread.o CWBinding.o WTPBinding.o WTPBcmDriverInteraction.o WTPSettingsFile.o timerlib.o  /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/lib/libssl.a  /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/lib/libcrypto.a  /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/lib/libpthread.a  /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/lib/libdl.a /home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1/staging_dir_mipsel/usr/lib/libpcap.a -D_REENTRANT -o WTP
WTP.o: In function `main':
/home/yang/trunk/capwap-0.93.3/WTP.c:410: undefined reference to `CWWTPReceiveStats'
/home/yang/trunk/capwap-0.93.3/WTP.c:422: undefined reference to `CWWTPReceiveFreqStats'
WTPRunState.o: In function `CWParseVendorMessage':
/home/yang/trunk/capwap-0.93.3/WTPRunState.c:1055: undefined reference to `CWParseVendorPayload'
WTPRunState.o: In function `CWSaveVendorMessage':
/home/yang/trunk/capwap-0.93.3/WTPRunState.c:1275: undefined reference to `CWWTPSaveUCIValues'
/home/yang/trunk/capwap-0.93.3/WTPRunState.c:1285: undefined reference to `CWWTPSaveWUMValues'
collect2: ld returned 1 exit status
make: *** [WTP] Error 1[root@SS-SERVER1 capwap-0.93.3]#


Makefile内容如下：
KAMIKAZEDIR=/home/yang/openwrt_sdk/OpenWrt-SDK-Linux-i686-1

CC = $(KAMIKAZEDIR)/staging_dir_mipsel/bin/mipsel-linux-gcc
LDFLAGS =  $(KAMIKAZEDIR)/staging_dir_mipsel/usr/lib/libssl.a  $(KAMIKAZEDIR)/staging_dir_mipsel/usr/lib/libcrypto.a  $(KAMIKAZEDIR)/staging_dir_mipsel/lib/libpthread.a  $(KAMIKAZEDIR)/staging_dir_mipsel/lib/libdl.a $(KAMIKAZEDIR)/staging_dir_mipsel/usr/lib/libpcap.a -D_REENTRANT

CFLAGS = -Wall -g -O0 -D_REENTRANT -DBCM -I $(KAMIKAZEDIR)/staging_dir_mipsel/usr/include #-DCW_NO_DTLS

# Memory leak
#LDFLAGS += ../dmalloc-5.5.0/libdmallocth.a
#CFLAGS += -DDMALLOC

# Capwap Debugging
CFLAGS += -DCW_DEBUGGING

RM = /bin/rm -f

# list of generated object files for WTP.
WTP_OBJS = WTP.o WTPBcmFrameReceive.o WTPConfigFile.o WTPProtocol.o WTPProtocol_User.o WTPDiscoveryState.o WTPJoinState.o WTPConfigureState.o WTPDataCheckState.o WTPRunState.o WTPRunStateCheck.o WTPRetransmission.o WTPSulkingState.o CWCommon.o CWConfigFile.o CWErrorHandling.o CWSafeList.o CWList.o CWLog.o CWNetwork.o CWProtocol.o CWRandom.o CWSecurity.o CWOpenSSLBio.o CWStevens.o CWThread.o CWBinding.o WTPBinding.o WTPBcmDriverInteraction.o WTPSettingsFile.o timerlib.o

WTP_SRCS = $(WTP_OBJS:.o=.c)

WTP_DEPS := $(WTP_OBJS:.o=.d)

# program executables.
WTP_NAME = WTP

.PHONY: deps clean clean_libs libs

# top-level rule, to compile everything.
all: $(WTP_NAME)

$(WTP_NAME): $(WTP_OBJS)
        $(CC) -DWRITE_STD_OUTPUT $(WTP_OBJS) $(CC_FLAGS) $(LDFLAGS) -o $(WTP_NAME)

clean:
        $(RM) $(WTP_NAME) $(WTP_OBJS) $(WTP_DEPS)

clean_deps:
        $(WTP_DEPS)

deps: $(WTP_SRC)
        $(CC) -MD -E -DWRITE_STD_OUTPUT $(WTP_SRCS) $(CFLAGS) >/dev/null

-include $(WTP_DEPS)

因为没有包含声明该函数的那个头文件，至于是哪一个文件，在命令行下man xxx就知道了，包含之。

另外，undefined reference之类的问题是没有包含相关的库。这个库你去找找README文件或INSTALL文件之类的文档，看一下有没有说明。反正要找到些什么蛛丝马迹的。
PS：看了下Makefile，有几个库，但不知道是不是相关的，不敢肯定。

太复杂了，在下不懂了。
本机编译通过，而交叉编译不通过，会不会是交叉编译器的问题？指向的库？库本身？都有可能。
比如./static/uclibc/libssl.a: could not read symbols: File in wrong format
它提示库的符号不能识别，一个可能的原因是这个库不是交叉编译过的版本。