问题解决方法：aarch64-linux-gnu/bin/ld: cannot find -lssl

错误：

/usr/lib/gcc-cross/aarch64-linux-gnu/5/…/…/…/…/aarch64-linux-gnu/bin/ld: cannot find -lssl
/usr/lib/gcc-cross/aarch64-linux-gnu/5/…/…/…/…/aarch64-linux-gnu/bin/ld: cannot find -lcrypto

分析原因：

aarch64-linux-gnu 工具本身没有包含openssl，所以需要把openssl安装到aarch64-linux-gnu指定的使用目录。

解决方法：

首先：使用–verbose | grep SEARCH_DIR ，去搜索aarch64-linux-gnu工具调用时，使用了哪个目录。

grayli@LinuxServer:~/test_case/iperf/demo3/iperf-3.6$ /usr/lib/gcc-cross/aarch64-linux-gnu/5/../../../../aarch64-linux-gnu/bin/ld --verbose | grep SEARCH_DIR
SEARCH_DIR("=/usr/local/lib/aarch64-linux-gnu"); SEARCH_DIR("=/lib/aarch64-linux-gnu"); SEARCH_DIR("=/usr/lib/aarch64-linux-gnu"); SEARCH_DIR("=/usr/local/lib"); SEARCH_DIR("=/lib"); SEARCH_DIR("=/usr/lib"); SEARCH_DIR("=/usr/aarch64-linux-gnu/lib");
grayli@LinuxServer:~/test_case/iperf/demo3/iperf-3.6$ /usr/lib/gcc-cross/aarch64-linux-gnu/5/../../../../aarch64-linux-gnu/bin/ld --verbose | grep SEARCH_DIR
SEARCH_DIR("=/usr/local/lib/aarch64-linux-gnu"); SEARCH_DIR("=/lib/aarch64-linux-gnu"); SEARCH_DIR("=/usr/lib/aarch64-linux-gnu"); SEARCH_DIR("=/usr/local/lib"); SEARCH_DIR("=/lib"); SEARCH_DIR("=/usr/lib"); SEARCH_DIR("=/usr/aarch64-linux-gnu/lib");

再次：（–prefix=/usr/aarch64-linux-gnu/lib/安装路径就是第一步搜索出来路径）

git clone https://github.com/openssl/openssl.git
cd openssl
git checkout OpenSSL_1_0_2-stable
./config --prefix=/usr/aarch64-linux-gnu/lib/ --cross-compile-prefix=aarch64-linux-gnu- no-asm shared
sed -i "s/-m64//g" Makefile
make
sudo make install

最后编译问题完美解决了！