Re: [Xen-devel] [PATCH] xl: Special case tap/aio for disk validation

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 28 Jan 2011, Jim Fehlig wrote:
> Currently, IIUC, the external script is invoked by udev
> 
> SUBSYSTEM=="xen-backend", KERNEL=="tap*", RUN+="/etc/xen/scripts/blktap
> $env{ACTION}"
> SUBSYSTEM=="xen-backend", KERNEL=="vbd*", RUN+="/etc/xen/scripts/block
> $env{ACTION}"
> 
> The block script will delegate to a helper if needed, which configures
> the block device and writes some info (like resulting dev node) to
> xenstore.  xend and/or qemu then read the info and continue configuring
> the device from backend perspective.
> 

When we add support for this to xl we are probably going to execute
these scripts directly. Having udev doing it for us doesn't simplify
things.


> > It shouldn't be too difficult but still non-trivial at this point of the
> > release cycle.
> > Maybe users could work around the lack of support in 4.1 calling the
> > script themselves and using the name of the block device in the VM
> > config file directly?
> >   
> 
> Yes, this is certainly a workaround.  One could argue this is the proper
> solution and remove support for external block scripts.  But this
> functionality has been around for years.

I think it is the best we can do for 4.1, given the timeframe available.

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