Re: [patch] [i386] Put hlt at the ON_STACK breakpoint [Re: GDB 7.4.91 available for testing]

Philippe Waroquiers
2012-07-26T21:56:20Z

On Wed, 2012-07-25 at 15:39 -0700, Joel Brobecker wrote:

> What I am trying to do, is make sure that new GDB versions work well
> with older versions of valgrind (although, isn't gdbserver support
> relatively recent?), while at the same time trying to make future
> versions of valgrind more robust. I don't know how long we are going
> to be able to keep the workaround. What if other tools implementing
> the remote protocol had the same problem, and they required us to
> insert a different instruction instead?
Valgrind gdbsrv appeared in the last Valgrind version (3.7.0).
If GDB modifies the stack to put a 0xCC, that should work with old
Valgrind (I will test in any case).

Otherwise, effectively, it is always possible that another "strange"
gdbserver must have another instruction.
I imagine however that a breakpoint trap instruction will be the
most likely common denominator amongst "strange" gdbserver.
The other "strange" gdbsrv I know about is the qemu one.
Just tried to build the last qemu to see how it works,
but build failed.

Philippe