[B2-devel] Direct Addressing and Darwin/MacOS X

[<gb...@di...>]

Hi,

I made some arrangements to sigsegv.cpp in order to support Darwin in
VOSF / direct addressing. The sole problem so far is that the usual
hacks for retrieving the fault address don't work there. Instead, we
currently need to decode the faultive instruction and read the address
from the saved register set. This hack comes from Boehm's garbage
collector 6.0alpha8 that comes from some other contributor.

Having said that, I have just realized Darwin doesn't honor the
protection flags passed to mmap() (say PROT_READ only). So, an explicit
mprotect() has to be done just after that. I am going to wrap a number
of mmap()/mprotect() functions to reflect that and also the fact that
Darwin doesn't support mapping memory from device files (MAP_ANON works
though).

Is it OK for the following functions going into src/Unix/vm_map.cpp ?
- address =3D vm_acquire(size)
- address =3D vm_acquire_fixed(address, size)
- void vm_release(address, size)
- rc =3D vm_protect(address, size, prot_flags) where prot_flags are:
  VM_PAGE_READ / VM_PAGE_WRITE / VM_PAGE_EXEC

This should also simplify some code in main_unix.cpp.

Note: vm_protect() exists in Mach/Darwin environments but with 4
arguments. This is not a problem since we use C++. Could this be a
problem for Objective C if Nigel wants to have the same naming
conventions ?

Bye,
Gwenol=E9.