From: Rik van Riel <riel@redhat.com>
Date: Fri, 21 Nov 2008 14:32:20 -0500
Subject: [xen] increase maximum DMA buffer size
Message-id: 20081121143220.08a94702@cuia.bos.redhat.com
O-Subject: [RHEL5.3 PATCH 3/3] xen: increase maximum DMA buffer size
Bugzilla: 412691
RH-Acked-by: Don Dutile <ddutile@redhat.com>
RH-Acked-by: Bill Burns <bburns@redhat.com>
RH-Acked-by: Glauber Costa <glommer@redhat.com>

After more investigation, we have got the reason of the panic. Currently
xen reserve 128M DMA buffer at most, while the on-board graphic card requires
256M memory. With following patch + xen patch + your patch in comments 30+31,
everything works quite well.

Fixes bug 412691

Signed-off-by: Jiang, Yunhong <yunhong.jiang@intel.com>
Signed-off-by: Rik van Riel <riel@redhat.com>

diff --git a/arch/x86/domain_build.c b/arch/x86/domain_build.c
index c72c300..8dcf816 100644
--- a/arch/x86/domain_build.c
+++ b/arch/x86/domain_build.c
@@ -138,12 +138,12 @@ static unsigned long __init compute_dom0_nr_pages(void)
     /*
      * If domain 0 allocation isn't specified, reserve 1/16th of available
      * memory for things like DMA buffers. This reservation is clamped to 
-     * a maximum of 128MB.
+     * a maximum of 384MB.
      */
     if ( dom0_nrpages == 0 )
     {
         dom0_nrpages = avail;
-        dom0_nrpages = min(dom0_nrpages / 16, 128L << (20 - PAGE_SHIFT));
+        dom0_nrpages = min(dom0_nrpages / 8, 384L << (20 - PAGE_SHIFT));
         dom0_nrpages = -dom0_nrpages;
     } else {
         /* User specified a dom0_size.  Do not clamp the maximum. */