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

[Xen-devel] Re: [Patch] Constrain DMADOM/swiotlb allocations to 1G phys

To: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [Patch] Constrain DMADOM/swiotlb allocations to 1G phys to fix b44 NIC driver
From: "Stephen C. Tweedie" <sct@xxxxxxxxxx>
Date: Tue, 28 Nov 2006 15:49:24 +0000
Delivery-date: Tue, 28 Nov 2006 07:49:41 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <1164728771.10380.15.camel@xxxxxxxxxxxxxxxxxxxxx>
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: <1164728771.10380.15.camel@xxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Hi,

On Tue, 2006-11-28 at 15:46 +0000, Stephen C. Tweedie wrote:

> It turns out that this 2GB / 31-bit constraint is magically hardcoded in
> a couple of places rather than being read correctly from config.h.  So
> this patch fixes that; changes config.h to specify a 1GB / 30-bit
> constraint for the DMADOM heap; and changes the x86/x86_64 swiotlb to
> request a 30-bit constraint for allocations of the swiotlb memory.

The 30 bit constraint is enough to let b44 work.  But there are a number
of sound cards which require a 28-bit DMA mask (256MB max physical
addressable memory).  1GB seems reasonably safe, but I'm much less
comfortable with restricting DMADOM to 256MB by default.  Does anyone
have any strong feelings about shifting this?  What other users of
DMADOM are there that might overflow if we restrict it even further?

Cheers,
 Stephen



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