Re: [Xen-devel] another xend race: qemu-dm versus device hotplug

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

John Levon writes ("[Xen-devel] another xend race: qemu-dm versus device 
hotplug"):
> +        status = xs_read(xsh, XBT_NULL, node, &len);
> +        if (status != NULL) {
> +            ret = (strcmp(status, "connected") == 0);
> +            goto out;
> +        }
> +        usleep(DEVICE_CREATE_INC);
> +        timeout -= DEVICE_CREATE_INC;
> +    } while (timeout > 0);

I agree that this is all a bit unpleasant really.  But waiting for the
device to be reported as ready in xenstore does seem more correct than
waiting for it to appear to stat.

The fly in the ointment is compatibility.  AFAICS this would make a
new qemu (one with this patch) not compatible with the old xend.  I
know it's a bit unfashionable but I'm trying to improve the
cross-version compatibility :-).

Perhaps xend could advertise in xenstore somehow that the new approach
was going to work ?

Ian.

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