ptrace single-stepping change breaks Wine
Andrew Morton
akpm at osdl.org
Tue Jan 4 15:21:11 CST 2005
Mike Hearn <mh at codeweavers.com> wrote:
>
> Also a precise description of what flex-mmap does would be good. Google
> wasn't too informative, best I could get was that it means mmap
> allocates from the "top" of the address space down. But where is the top
> exactly?
Ingo has described it thus:
before:
0x08000000 ... binary code
0x08xxxxxx ... brk area
0x40000000 ... start of mmap, new mmaps go after old ones
0xbfxxxxxx ... stack
after:
0x08000000 ... binary code
0x08xxxxxx ... brk area
0xbfxxxxxx ... _end_ of all mmaps, new mmaps go below old ones
0xbfyyyyyy ... stack
the 'after' layout guarantees that brk area (malloc()) can grow
unlimited and mmap() can grow unlimited - they will meet somewhere
inbetween when almost all of the VM is used up. [the 'top' of the mmaps
in the 'after' layout is constrained by the stack ulimit - the stack
must still fit and we never allocate into the stack's yet unallocated
and growable hole.]
with the 'before' layout we've got 900 MB for brk() and 1.9GB for
mmaps() - a rigid limit.
More information about the wine-devel
mailing list