Large-Address awareness on 64 bit systems

[Ryan Johnson]

On 21/06/2011 4:21 AM, Corinna Vinschen wrote:
> Hi Ryan,
>
> On Jun 18 16:32, Ryan Johnson wrote:
>> - deliberately dlopen-ing two dlls with the same base address and
>> trying to fork
> http://cygwin.com/ml/cygwin-apps/2011-06/msg00047.html
>
> Did you try the ASLR flag for your test DLLs?  Does it help, perhaps?
> If the ASLR flag works as I understand it, the DLLs should be moved
> into a less dangerous memory area and be then fixed there.
ASLR works pretty well for dlls having static use patterns (including 
apps which always open the same dlls), from what I can tell. The reason 
I hadn't done it for that test app is because dlls created and loaded 
dynamically by apps like gcc bootstrap wouldn't have it set either, and 
I wanted a consistent way to reproduce the erratic fork problems that 
they see as a result of the odd base address collision. Similarly, I 
purposefully avoided rebasing or ASLR-ing my cygwin install while 
testing the fork patches.

Ryan