升级了php5.2到5.3之后，或者是php有重新编译过之后，可能遇到这样的情况：
[root@See341-98 ~] # /usr/local/php/bin/php -m|grep mysql
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
/usr/local/php/bin/php: /usr/lib64/libxml2.so.2: no version information available (required by /usr/local/php/bin/php)
mysql解决的办法很简单：
# mv /usr/lib64/libxml2.so.2 /usr/lib64/libxml2.so.2_backup
# ln -s /usr/lib/libxml2.so.2 /usr/lib64/libxml2.so.2