Messages in this thread | | | Date | Fri, 9 May 2003 13:52:17 +0200 | From | mikpe@csd ... | Subject | Re: hammer: MAP_32BIT |
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Andi Kleen writes: > > On Fri, May 09, 2003 at 01:28:11PM +0200, mikpe@csd.uu.se wrote: > > I have a potential use for mmap()ing in the low 4GB on x86_64. > > Just use MAP_32BIT
Will that be corrected to use the full 4GB space? 2GB is too small.
> > Sounds like your MAP_32BIT really is MAP_31BIT :-( which is too limiting. > > What about a more generic way of indicating which parts of the address > > space one wants? The simplest that would work for me is a single byte > > 'nrbits' specifying the target address space as [0 .. 2^nrbits-1]. > > This could be specified on a per-mmap() basis or as a settable process attribute. > > On x86-64 an mmap extension for that would be fine, but on i386 you get > problems because mmap64() already maxes out the argument limit and you > cannot add more.
This would only be used on x86_64. i386 compat is a non-issue. (This is for runtime systems stuff, not applictions.)
> prctl is probably better. You really want [start; end] right ?
I just want mmap() to return addresses that fit in 32 bits.
MAP_32BIT would do nicely, if it wasn't limited to 2GB.
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