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] blkfront/back and sector size of 2048 with CDROM's

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, "xen-devel" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] blkfront/back and sector size of 2048 with CDROM's
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Tue, 5 Feb 2008 21:01:11 +1100
Delivery-date: Tue, 05 Feb 2008 02:01:40 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <C3CDD6D1.134AE%Keir.Fraser@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/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>
References: <AEC6C66638C05B468B556EA548C1A77D0131AAC9@trantor> <C3CDD6D1.134AE%Keir.Fraser@xxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Achni2ggR2p2caN2Szy4krhWTtOFHgARf1zQAAByYdAAALAy6gAB3hWg
Thread-topic: [Xen-devel] blkfront/back and sector size of 2048 with CDROM's
> Yes, except that last_sect = 5, because it's an inclusive range.

Yes. :)

> I'm pretty sure you can DMA to/from unaligned buffers (e.g., in this
case
> non-2kB aligned). Certainly blkback doesn't appear to check for it, so
> presumably we found it works!

My buffers are always page aligned anyway. I have no control over the
buffer alignment that windows gives me, so I have to copy the data back
and forth. In a previous version I would check for buffer alignment
first (windows almost always gives you buffers aligned to a page
boundry), but the windows scsi controller interface is really messed
up... you are always called at a really high irq level, and the routines
for mapping buffers to pfn's are not available in that situation.

James

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