On 19.11.2021 21:29, Stefano Stabellini wrote: > --- a/drivers/xen/xenbus/xenbus_probe.c > +++ b/drivers/xen/xenbus/xenbus_probe.c > @@ -951,6 +951,20 @@ static int __init xenbus_init(void) > err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v); > if (err) > goto out_error; > + /* Uninitialized. */ > + if (v == 0 || v == ULLONG_MAX) { Didn't you have a comment in v1 here regarding the check against 0? Or was that just like now only in the description? IOW I think there ought to be a code comment justifying the theoretically wrong check ... Also, while I realize there are various other similar assumptions elsewhere, I would generally recommend to avoid such: There's no guarantee that now and forever unsigned long long and uint64_t are the same thing. And it's easy in cases like this one: if (!v || !(v + 1)) { Jan