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] Re: [PATCH 1 of 7] x86: add _PAGE_IOMAP pte flag for IO

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH 1 of 7] x86: add _PAGE_IOMAP pte flag for IO mappings
From: Avi Kivity <avi@xxxxxxxxxxxx>
Date: Wed, 10 Sep 2008 12:55:25 +0300
Cc: Ingo Molnar <mingo@xxxxxxx>, Xen Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Andi Kleen <andi@xxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, "H. Peter Anvin" <hpa@xxxxxxxxx>
Delivery-date: Wed, 10 Sep 2008 02:55:47 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <48C68EA3.4050508@xxxxxxxxxxxx>
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <4d93ba619c716c45cca0.1220826073@localhost> <48C67AE0.5060503@xxxxxxxxxxxx> <48C68C6B.7030803@xxxxxxxx> <48C68EA3.4050508@xxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird 2.0.0.16 (X11/20080723)
Avi Kivity wrote:

I'm not sure; I still don't really understand how _PAGE_SPECIAL gets
used, other than being user-mode mapping only.  But in principle,
_PAGE_IOMAP could be set on both kernel and user mappings (if you direct
map a device into a process address space), so I think they would
conflict then?


It's a "don't refcount me" flag, which is not sematically the same as I/O, but may be close enough.

Actually it's more of a "no struct page" flag, which implies no refcounting. And not having a struct page should correspond well to a pte not requiring pfn->mfn conversion and being an I/O page.

--
error compiling committee.c: too many arguments to function


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

<Prev in Thread] Current Thread [Next in Thread>