WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel] passing hypercall parameters by pointer

To: "Hollis Blanchard" <hollisb@xxxxxxxxxx>, "Sharma, Arun" <arun.sharma@xxxxxxxxx>
Subject: RE: [Xen-devel] passing hypercall parameters by pointer
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Thu, 18 Aug 2005 14:56:23 +0800
Cc: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>, Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Yu, Ke" <ke.yu@xxxxxxxxx>, "Ling, Xiaofeng" <xiaofeng.ling@xxxxxxxxx>
Delivery-date: Thu, 18 Aug 2005 06:55:00 +0000
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcWjeNZ42h3hEbg7RTycd09qwOTnkQAPwnkw
Thread-topic: [Xen-devel] passing hypercall parameters by pointer
>From: Hollis Blanchard
>Sent: Thursday, August 18, 2005 6:11 AM
>
>I have no answer for parameters that are very large, but I wonder how
many
>cases there are. For example, DOM0_READCONSOLE could just be limited
>to 4KB
>reads, and if there's more data than that, call it again. Perhaps there
is
>some case-specific solution to xc_get_pfn_list() as well.
>

If one hypercall wants to get specific context at one point atomically,
"call it again" several times actually returns mixed contexts belonging
to different time points. That's not desired. Even if people want to add
atomic protection for such type of case, performance will be affected a
lot and more risk to suffer dead-lock.

Thanks,
Kevin

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel