From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Shuklin Subject: Re: Dom0 IO handling Date: Fri, 19 Oct 2012 05:48:08 +0400 Message-ID: <5080B158.6030908@gmail.com> References: <1349936188.70593.YahooMailNeo@web120006.mail.ne1.yahoo.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============8326202991560825680==" Return-path: In-Reply-To: <1349936188.70593.YahooMailNeo@web120006.mail.ne1.yahoo.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org This is a multi-part message in MIME format. --===============8326202991560825680== Content-Type: multipart/alternative; boundary="------------030909090509070501010003" This is a multi-part message in MIME format. --------------030909090509070501010003 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit AFAIK dom0 is pv-domain. All interrupts are handled by xen and passed down to dom0 via events (kinda internal xen interrupt-like stuff). PV kernel accepts them and process as normal interrupts. Is Xen use IOMMU to protect itself from misbehave devices or not... I'm not sure. On 11.10.2012 10:16, maheen butt wrote: > Hi all, > > I'm investigating the source code of Xenified kernel. From > documentations related to > Xen told me that all guest domains run in less privilege mode ( ring 1 > in case of x86). > Dom0 is also running in ring 1. But it can have direct access to IO > devices. It means > Dom0 has a special bahaviour that it is running in ring1 but can > directly access IO devices. > How Dom0 access IO devices directly? > how can I relate this special way of Dom0 with its source code? > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel --------------030909090509070501010003 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit AFAIK dom0 is pv-domain.
All interrupts are handled by xen and passed down to dom0 via events (kinda internal  xen interrupt-like stuff). PV kernel accepts them and process as normal interrupts.

Is Xen use IOMMU to protect itself from misbehave devices or not... I'm not sure.

On 11.10.2012 10:16, maheen butt wrote:
Hi all,

I'm investigating the source code of Xenified kernel. From documentations related to
Xen told me that all guest domains run in less privilege mode ( ring 1 in case of x86).
Dom0 is also running in ring 1. But it can have direct access to IO devices. It means
Dom0 has a special bahaviour that it is running in ring1 but can directly access IO devices.
How Dom0 access IO devices directly?
how can I relate this special way of Dom0 with its source code?


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