Re: Cygwin bash's built-in test command crashes on Windows 2008 Server 64bit under KVM

[Matteo Frigo <athena@fftw.org>]

Avi Kivity <avi@redhat.com> writes:

> - add a watchpoint to break when the value of gs:[0x30] changes

It seems that the problem can be reproduced by compiling the following
simple program using cygwin's gcc.  The program crashes on w2k3-amd64
on kvm-83 on core2-duo, and it does not crash on the same w2k3-amd64
installation on kvm-83 on AMD Phenom.

  #include <setjmp.h>

  jmp_buf env;
  main()
  {
       if(setjmp(env)) return;
       longjmp(env, 1);
  }

The problem seems to be in the instruction ``mov gs,ax'' (Intel
syntax) in the longjmp() code.  If I let the virtual machine execute
the instruction, the program crashes.  However, if I step over the
instruction using the vs2008 debugger, the program completes without
crashing.  Thus, I think that this is the instruction that Avi is
looking for, but I don't know how to proceed from here.

Hope this helps.
Cheers,
Matteo Frigo