@a1ba >in which case the licensing doesn't play any role (as GPL explicitly refers to it as "System Libraries").
glibc is licensed under the LGPLv2.1-or-later and if you compile software against it, you need to meet the requirements of allowing the user to modify the library and debug their modifications (even via reverse engineering).

The "system libraries" exception in the GPLv3 is a limited exception, allowing for a GPLv3+ program to be linked to an existing proprietary libc on a proprietary OS for example, without permitting the writing of proprietary derivative works.


glibc malloc is not the fastest or most memory-efficient malloc, but it is the fastest malloc that is portable and also memory-efficient - it's all a tradeoff and glibc malloc makes the best tradeoffs.