control the immutability of
system call changes currently mapped pages in the region to be marked
immutable, which means their protection or mapping may not be changed in the
future. mmap(2), mprotect(2), and
to pages marked immutable will return with error
Unmapped pages in the region do not retain immutability, but this behaviour should not be relied upon.
Not all implementations will guarantee that the immutable characteristic can be set on a page basis; the granularity of changes may be as large as an entire region.
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
mimmutable() system call will fail
- The virtual address range specified by the addr and len arguments is not valid.
mmap(2), mprotect(2), munmap(2)
mimmutable() function first appeared
in OpenBSD 7.3.
At present, mprotect(2) may reduce permissions on immutable pages marked
the less permissive
PROT_READ. This one-way
operation is permitted for an introductory period to observe how software
uses this mechanism. It may change to require explicit mutable region
and explicit calls to