Wine and mmap

John Birrell jb at
Fri Aug 27 21:09:39 PDT 2004

On Sat, Aug 28, 2004 at 12:01:18AM -0400, Brian Fundakowski Feldman wrote:
> Is the problem that it specifically runs out of memory area but it's not
> checking where it needs to?  If so, I think you could hash out the solution
> with a wrapper/workaround mmap() in userland first.

The problem is that if the mmap kernel code is left to choose a map address,
it tries to use memory above the highest value allocated. This conflicts with
Wine because Wine needs to reserve the top half of a process' address space
to be compatible with Win9X programs.

Wine gobbles the upper memory as soon as it can (i.e. just after the base
Wine process is loaded with it's linked libraries - libc). Once the memory
has been reserved, Wine then goes ahead and loads the "DLL" libraries using
the standard dlopen() call. The first one Wine tries to load fails because
the upper-most address used by that time is the top of the process address
space and it all ends in tears.

What the mmap code needs (IMHO) to do is to find a hole in the address space
if the upper memory is all allocated.

John Birrell

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