Re: AMAP_SHARED (was Re: XIP)

[Masao Uebayashi <uebayasi%tombi.co.jp@localhost>]

A few more comments:

- AMAP_SHARED itself is a fine concept; it's used by shared memory.

        sys/kern/sysv_shm.c:
            452         error = uvm_map(&vm->vm_map, &attach_va, size, uobj, 0, 
0,
            453             UVM_MAPFLAG(prot, prot, UVM_INH_SHARE, 
UVM_ADV_RANDOM, flags));

  (Note UVM_INH_SHARE == MAP_INHERIT_SHARE).

  I guess MAP_INHERIT_SHARE was added because adding it was easy
  after shared amap was implemented for shared memory?

- For highly tuned, XIP'ed systems, programs should be designed to
  avoid .data, because they're COW'ed to page cache sooner or later.