1) uClibc is smaller than glibc. We attempt to maintain a glibc compatible interface, allowing applications that compile with glibc to easily compile with uClibc. However, we do not include _everything_ that glibc includes, and therefore some applications may not compile. If this happens to you, please report the failure to the uclibc mailing list, with detailed error messages. //体积小 2) 2) uClibc is much more configurable then glibc. This means that a developer may have compiled uClibc in such a way that significant amoun ts of functionality have been omitted. 可以根据选择进行配置编译 3) 3) uClibc does not even attempt to ensure binary compatibility across releases. When a new version of uClibc is released, you may or may not need to recompile all your binaries. 4) malloc(0) in glibc returns a valid pointer to something(!?!?) while in uClibc calling malloc(0) returns a NULL. The behavior of malloc(0) is listed as implementation-defined by SuSv3, so both libraries are equally correct. This difference also applies to realloc(NULL, 0). I personally feel glibc's behavior is not particularly safe. To enable glibc behavior, one has to explicitly enable the MALLOC_GLIBC_COMPAT option. 我个人感觉的glibc的行为不是特别安全。启用glibc的行为，人们必须明确启用MALLOC_GLIBC_COMPAT选项。 4) 4.1) glibc's malloc() implementation has behavior that is tunable via the MALLOC_CHECK_ environment variable. This is primarily used to provide extra malloc debugging features. These extended malloc debugging features are not available within uClibc. There are many good malloc debugging libraries available for Linux (dmalloc, electric fence, valgrind, etc) that work much better than the glibc extended malloc debugging. So our omitting this functionality from uClibc is not a great loss. 的glibc的malloc（）实现了行为是可调通过MALLOC_CHECK_环境变量。这主要是用来提供额外的malloc调试功能。这些扩展的malloc调试功能都没有可在uClibc的。有很多很好的malloc调试库可用于Linux（dmalloc，电围栏，Valgrind的，等等），其工作多比glibc的扩展malloc调试好。因此，我们忽略了此从uClibc的功能是不是一个巨大的损失。 5) uClibc does not provide a database library (libdb). 6) uClibc does not support NSS (/lib/libnss_*), which allows glibc to easily support various methods of authentication and DNS resolution. uClibc only supports flat password files and shadow password files for storing authentication information. If you need something more complex than this, you can compile and install pam. 7) uClibc's libresolv is only a stub. Some, but not all of the functionality provided by glibc's libresolv is provided internal to uClibc. Other functions are not at all implemented. 8) libnsl provides support for Network Information Service (NIS) which was originally called "Yellow Pages" or "YP", which is an extension of RPC invented by Sun to share Unix password files over the network. I personally think NIS is an evil abomination and should not be used. These days, using ldap is much more effective mechanism for doing the same thing. uClibc provides a stub libnsl, but has no actual support for Network Information Service (NIS). We therefore, also do not provide any of the headers files provided by glibc under /usr/include/rpcsvc. 9) uClibc's locale support is not 100% complete yet. We are working on it. 10) uClibc's math library only supports long double as inlines, and even then the long double support is quite limited. Also, very few of the float math functions are implemented. Stick with double and you should be just fine. 11) uClibc's libcrypt does not support the reentrant crypt_r, setkey_r and encrypt_r, since these are not required by SuSv3. 12) uClibc directly uses kernel types to define most opaque data types. 13) uClibc directly uses the linux kernel's arch specific 'stuct stat'. 14) uClibc's librt library currently lacks all aio routines, all clock routines, and all shm routines (only the timer routines and the mq routines are implemented).