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

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

Hi,

> 2) Sounds like you have had more success than I.
>    I wasn't able to use _any_ mmap() calls under OS X.
>    (it always gives an errno that says the function is unimplemented)

Indeed, mmap() does not work when you specify a file to map from.
Instead, simply add MAP_ANON to the list of flags and set the file
descriptor to -1.

> 3) You may want to investigate the map_fd(), vm_allocate() and
>    vm_deallocate() calls in this old Rhapsody (NextStep) document:

Thanks, I have just added those system calls. Unfortunately, B2 still
crash in some select() in either implementation (vm_allocate() or
mmap()). I thought it may be due to the select() call in Delay_usec()
but turning the select() to an usleep() still makes B2 to crash.

Actually, as I supposed earlier, the crashing behavior appears when VOSF
is enabled (use_vosf =3D true in video_x.cpp). That may be due to some
combination of signal/sigsegv handler/vm_protect/...

VideoRefresh() didn't have a chance to get called. Instead, the screen
remains black and logging shows me that only a few pages get unprotected
before crashing in supposedly select(), ... on a branch instruction!?

As a temporary workaround, I think i will disable VOSF in Darwin but
still do direct addressing. That works and provides an interesting
speedup (15-25%).

> > 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 ?
>=20
>       Won't be a problem, as my MacOS X port currently doesn't use
> main_unix.cpp anyway. (most of its stuff is in cpp_glue_MacOSX.cpp)

OK. BTW, is it advanced enough now so that it could be integrated into
CVS ?

Bye;
Gwenol=E9.