Andrew Lyon wrote:

> How do you introduce the delay? I'd like to try xen-unstable with
> viridian=1 but I want to be absolutely sure that the issue is fixed so
> if you have a patch for qemu-dm I'd appreciate it if you could post
> it, the BSOD 101 issue causes serious problems for me because I am
> using pci passthrough, I've found  if the domain using passthru
> crashes, I issue "xm pci-detach", or "xm destroy" a domain that is
> using a passthru pci device, will cause the entire machine to lockup ,
> I've tried Xen 3.2.1/2/3 and 3.3.0/1 with various different kernels
> but it always happens, so if my Vista or 2008 domains that are using
> pci passthru usb2 cards BSOD at all it takes down the entire box,
> usually resulting in data loss :(
> 
> Perhaps that problem might be fixed in unstable too, I will try it
> tomorrow but it would really help to have a way to trigger a bsod 101.

I use the attached change to qemu. In cpu_handle_ioreq, if send_vcpu != 
0,, it checks for the presence of a file called /tmp/qemu_delay. If it 
exists, it opens it and reads a delay value from it. Then it sleeps for 
that duration (in microseconds).

What I do is boot windows 2008, then open an editor to edit 
/tmp/qemu_delay. From the editor, I write various values to it. An easy 
way to trigger the issue is to write a large value (say, 8000000 for 8 
seconds), wait a little while, and then write 0 to make the domain come 
back to life. It should bluescreen at this point. Sometimes the 
procedure has to be repeated a few times.

If you want to do "echo $value > /tmp/qemu_delay", you'll need to change 
the hack to re-open the file each time, probably.

- Frank