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] Failure to get memory for GATT table, again

To: Jacob Gorm Hansen <jacobg@xxxxxxx>
Subject: Re: [Xen-devel] Failure to get memory for GATT table, again
From: Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>
Date: Tue, 01 Feb 2005 22:45:49 +0000
Cc: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxxx>, Ian.Pratt@xxxxxxxxxxxx
Delivery-date: Tue, 01 Feb 2005 22:48:41 +0000
Envelope-to: xen+James.Bulpin@xxxxxxxxxxxx
In-reply-to: Your message of "Tue, 01 Feb 2005 23:15:53 +0100." <20050201221553.GA15851@xxxxxxx>
List-archive: <http://sourceforge.net/mailarchive/forum.php?forum=xen-devel>
List-help: <mailto:xen-devel-request@lists.sourceforge.net?subject=help>
List-id: List for Xen developers <xen-devel.lists.sourceforge.net>
List-post: <mailto:xen-devel@lists.sourceforge.net>
List-subscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=subscribe>
List-unsubscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=unsubscribe>
Sender: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx
> hmm, actually it seems the case is that dma_alloc_coherent() falls back to
> calling __get_free_pages(), because dev->dma_mem is NULL. When the returned
> address gets converted into a bus address, the resulting address seems to be 
> within Xen-space :-(
> 
> Why is calling __get_free_pages() a problem?

The AGP aperture needs a set of machine contiguous pages, whereas
get_free_pages will only give you pseudo-physical contiguous.

Drivers are supposed to use the former (for reasons of ensuring
DMA coherence) , but the agp drivers seem particularly shoddy,
probably because they've only ever been used on x86.

Ian


-------------------------------------------------------
This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting
Tool for open source databases. Create drag-&-drop reports. Save time
by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc.
Download a FREE copy at http://www.intelliview.com/go/osdn_nl
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel