Re: hammer: MAP_32BIT

[Edgar Toernig]

> > Anyway, what's so bad about the idea someone (Linus?) suggested?
[it was Andi]
> > Without MAP_FIXED the address given to mmap is already taken as a
> > hint where to start looking for free memory.
> 
> The kernel fortunately already defines some semantics to using a
> non-NULL first parameter without MAP_FIXED.  It means: I prefer
> *exactly* this address.

Yeah, ok.

>  If it's not available, give me anything else.

And at least on older kernels (don't know about 2.5) it gives you
not "anything" but the next free memory region above that address.

POSIX-draft6 about that topic:

    "A non-zero value of addr is taken to be a suggestion of a
     process address near which the mapping should be placed."

> Now you want to give this another semantics.  It would need at least one
> more MAP_* flag.

No new flag.  No new semantic.  Everything's already there...

Ciao, ET.