This tunable namespace supports operations that affect the way the GNU C Library and the process manage memory.
If the hardware supports memory tagging, this tunable can be used to control the way the GNU C Library uses this feature. At present this is only supported on AArch64 systems with the MTE extention; it is ignored for all other systems.
This tunable takes a value between 0 and 255 and acts as a bitmask that enables various capabilities.
Bit 0 (the least significant bit) causes the
subsystem to allocate
tagged memory, with each allocation being assigned a random tag.
Bit 1 enables precise faulting mode for tag violations on systems that support deferred tag violation reporting. This may cause programs to run more slowly.
Bit 2 enables either precise or deferred faulting mode for tag violations whichever is preferred by the system.
Other bits are currently reserved.
The GNU C Library startup code will automatically enable memory tagging support in the kernel if this tunable has any non-zero value.
The default value is ‘0’, which disables all memory tagging.