Eyes Above The Waves

Monday 20 April 2015

Another VMWare Hypervisor Bug

Single-stepping through instructions in VMWare (6.0.4 build-2249910 in my case) with a 32-bit x86 guest doesn't trigger hardware watchpoints.

Steps to reproduce:

1. Configure a VMWare virtual machine (6.0.4 build-2249910 in my case) booting 32-bit Linux (Ubuntu 14.04 in my case).
2. Compile this program with gcc -g -O0 and run it in gdb:

   int main(int argc, char** argv) {
     char buf[100];
     buf[0] = 99;
     return buf[0];
   }

3. In gdb, do
   1. break main
   2. run
   3. watchpoint -l buf[0]
   4. stepi until main returns
4. This should trigger the watchpoint. It doesn't :-(.

Doing the same thing in a KVM virtual machine works as expected.

Sigh.