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37.7 Memory Related Tunables

Tunable namespace: glibc.mem

This tunable namespace supports operations that affect the way the GNU C Library and the process manage memory.

Tunable: glibc.mem.tagging

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 malloc 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.

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.