Re: [Qemu-devel] qemu-user: relocating target code weakness

[Stefano Bonifazi]

On 01/26/2011 09:19 PM, Richard Henderson wrote:
> On 01/26/2011 12:17 PM, Lluís wrote:
> > Richard Henderson writes:
> >
> > > On 01/26/2011 03:07 AM, Stefano Bonifazi wrote:
> > > > P.S. Please just answer that last question, whether it is possible to
> > > > have a variable showing the upper bound of heap (some brk_end) for a
> > > > target process
> > > No, the heap grows until it reaches some other memory mapped entity.
> > > From man brk(2) :
> >
> >       "sbrk() increments the program's data space by increment bytes.
> >        Calling sbrk() with an increment of 0 can be used to find the
> >        current location of the program break."
> >
> > I already sent this to the list in a previous mail, but it seems you
> > overlooked it as you were not an explicit recipient.
> That's the current top of the heap.  I answered the question as if
> it was asking for the maximum top of the heap.
>
>
> r~
Yup!
I am concerned what can be the highest address used as heap by a target 
binary, because I am creating multiple instances of qemu-user, and I 
wanna prevent the target process images and heaps to overlap..
Good enough to know the mmu will stop giving memory when meeting another 
memory mapped region..
Moreover I think I'd have to call sbrk from within the target binary for 
resizing its heap, whereas I wanna control it from qemu-user that is 
loading, then translating and executing it..
@Luis: Yup sorry for not answering the previous post of yours, I thought 
I'd receive emails always when somebody answered a post I created at the 
beginning!

Thank you!
Regards,
Stefano B.