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From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Anthony Liguori <aliguori-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
Cc: kvm-devel <kvm-devel-TtF/mJH4Jtrk1uMJSBkQmQ@public.gmane.org>
Subject: Re: Userspace hypercalls?
Date: Mon, 27 Aug 2007 19:47:22 +0300	[thread overview]
Message-ID: <46D3001A.9070706@qumranet.com> (raw)
In-Reply-To: <46D2FCE1.7020605-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Avi Kivity wrote:
>
> Thinking a little more about this, it isn't about handling hypercalls 
> in userspace, but about handling a virtio sync() in userspace.
>
> So how about having a KVM_HC_WAKE_CHANNEL hypercall (similar to Xen's 
> event channel, but assymetric) that has a channel parameter.  The 
> kernel handler for that hypercall dispatches calls to either a kernel 
> handler or a userspace handler.  That means we don't need a separate 
> ETH_SEND, ETH_RECEIVE, or BLOCK_SEND hypercalls.

And thinking a tiny little bit more about this, we can have the kernel 
(optionally) fire an eventfd, so a separate userspace thread or process 
can be woken up to service the device, without a heavyweight exit.

-- 
Any sufficiently difficult bug is indistinguishable from a feature.


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  parent reply	other threads:[~2007-08-27 16:47 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-27 15:27 Userspace hypercalls? Anthony Liguori
2007-08-27 16:16 ` Avi Kivity
     [not found]   ` <46D2F8FA.6050104-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-08-27 16:19     ` Avi Kivity
2007-08-27 16:33     ` Avi Kivity
     [not found]       ` <46D2FCE1.7020605-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-08-27 16:47         ` Avi Kivity [this message]
     [not found]           ` <46D3001A.9070706-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-08-27 17:32             ` Anthony Liguori
2007-08-27 17:36               ` Avi Kivity
     [not found]                 ` <46D30BAE.4080705-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-08-27 17:47                   ` Anthony Liguori
     [not found]                     ` <46D30F15.6050601@qumranet.com>
     [not found]                       ` <46D30F15.6050601-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-08-27 19:58                         ` Luca
     [not found]                           ` <68676e00708271258o278de93ek8a051619dd03fb6a-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-08-27 20:01                             ` Avi Kivity
     [not found]                               ` <46D32DA8.1080900-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-08-27 21:06                                 ` Anthony Liguori
2007-08-29  6:59         ` Dor Laor
     [not found]           ` <64F9B87B6B770947A9F8391472E032160D6558D8-yEcIvxbTEBqsx+V+t5oei8rau4O3wl8o3fe8/T/H7NteoWH0uzbU5w@public.gmane.org>
2007-08-29 21:24             ` Avi Kivity
     [not found] <46D326020200005A00029BFF@mcclure.wal.novell.com>
     [not found] ` <46D326080200005A00029C02-Igcdv/6uVdMHoYOw/+koYqIwWpluYiW7@public.gmane.org>
2007-08-27 23:29   ` Gregory Haskins

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