[Qemu-devel] Re: Problem with watchpoint in gdbstub

[Jan Kiszka]

Jun Koi wrote:
> Hi,
> 
> I am trying to debug a VM using gdb. I connected gdb to Qemu (latest
> code from git repo), and issued below command:
> 
> ...
> (gdb) watch *0x77f44cd8
> (gdb) c
> 
> The idea is to catch the write access to address 0x77f44cd8.
> 
> But after the "c" command, I saw that the window title of my VM
> continuously flip between "QEMU [Stopped]" and "QEMU", non-stop.
> This makes the VM unusable.
> 
> Is it a bug? Anybody sees the same problem?

I would bet your watchpoint was established by gdb as a software
watchpoint. In that case gdb will step through the target, checking
after each instruction if the memory changed.

Is that address valid at the time gdb wants to install it? I saw gdb
choosing a software watchpoint before when it wasn't.

Jan

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