From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: RFC Userspace hypercalls
Date: Wed, 6 Jan 2016 16:41:18 +0000
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To: Jan Beulich <JBeulich@suse.com>, Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Keir Fraser <keir@xen.org>, Tim Deegan <tim@xen.org>, Xen-devel List <xen-devel@lists.xen.org>
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On 06/01/16 16:31, Jan Beulich wrote:
>>>> On 06.01.16 at 15:44, <andrew.cooper3@citrix.com> wrote:
>> We did have an internal request for an HVM guest userspace netfront
>> driver to be able to use evntchnop calls directly.
> 
> And this can't be accomplished using the evtchn and/or privcmd
> drivers?

It can and should be done with the evtchn driver.

Even for tests I think it should return to kernel mode to perform
hypercalls.  Tests should not run in a "magic" mode that normal guests
won't use.

If there are failure cases where return to kernel isn't possible and
some logging would be useful, perhaps writing to a memory buffer and
retrieving this via a crash dump would be ok?

David