Linux Kernel 5.5 support code for the eventual elimination of the sysctl system call, the code has been abandoned for about ten years, currently has no effect on any modern system architecture.
For a long time, Linux sysctl system call is not recommended to be used, it is not recommended for use with sysctl interface via / proc / sys public, which is / kernel system attributes set the preferred method of reading. Linux Kernel 5.5 did not involve changes to / proc / sys support, but only the binary system with sysctl interface should call delete on Linux has been unused for many years.
Linux kernel team in the mail representation, we understand that no one should have enabled sysctl system call, do not rule out some people still turn it on in a few defconfigs, although such cases are very rare. If there is anyone who wants to call this system, they may need to restore patch.
In fact, back in 2011, they wanted to remove the code, but the need to maintain compatibility, can not be completely removed. At that time, the rest of the code for compatibility with older C libraries, but now the building any person not want to run Linux 5.5 are super old-fashioned libc.
Eric W. Biederman wrote a patch that removed the system call, he mentioned previously "linux-next has a new xtensa defconfig, which allows the system to call this cycle, but the code did not mean defenders replied enabled." from today's linux-next tree began, defconfig system call is no longer active.
Source: Phoronix