"kernel" heap idea

DJ Delorie dj@delorie.com
Tue Jan 4 16:03:00 GMT 2000

> We rely on the fact that memory is available at the same location for
> fork so if this breaks we have serious problems anyway.

OK.  I didn't think this would be a problem, but the documentation
does specifically state that you can't rely on it.  I assumed that if
we did the allocation near program startup, we'd be able to get the
same spot each time.

> Also, as long as the memory doesn't contain internal references to
> itself, you could get by with relocation.

Not if it's shared.  Relocating for one app would break the others.

> It doesn't let you expand a region but you can use the same mechanism
> as we do for the heap where you set aside a region but don't really
> allocate it.

Is that the option for non-committed mappings, with VirtualAlloc later?

> If we are going to be inventing some kind of malloc-like allocation
> in cygwin, it would be nice (tm) to also have a completely separate
> malloc heap for cygwin itself.

You mean a per-process cygwin-private heap?  In addition to the global
shared heap?  Hmmm...

> I think that we could generalize the malloc in newlib to handle
> multiple heaps.

We'd have to be careful not to break other newlib-using tools.

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