From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pasi =?iso-8859-1?Q?K=E4rkk=E4inen?= <pasik@iki.fi>
Subject: Re: 2.6.38 (FC15) with PCI passthrough fails
	mysteriously with iommu=soft..
Date: Thu, 2 Jun 2011 23:49:14 +0300
Message-ID: <20110602204914.GT32595@reaktio.net>
References: <4DE60EF8.5060902@redhat.com> <4DE61C2A.2000006@redhat.com>
	<20110601143100.GE4081@dumpdata.com> <4DE677C6.6040701@redhat.com>
	<20110601181317.GA2455@dumpdata.com>
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To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Laszlo Ersek <lersek@redhat.com>
List-Id: xen-devel@lists.xenproject.org

On Wed, Jun 01, 2011 at 02:13:17PM -0400, Konrad Rzeszutek Wilk wrote:
> On Wed, Jun 01, 2011 at 07:32:54PM +0200, Laszlo Ersek wrote:
> > On 06/01/11 16:31, Konrad Rzeszutek Wilk wrote:
> > >On Wed, Jun 01, 2011 at 01:02:02PM +0200, Laszlo Ersek wrote:
> > >>(Perhaps it's best to write a separate mail about this.)
> > >
> > >Yes. You did use 'iommu=soft' on your bootup line right?
> > 
> > I thought I did; turns out I was wrong. Sorry for the noise.
> > 
> > Now I tried with "iommu=soft swiotlb=force", but this way the guest
> 
> You don't need the swiotlb=force. I wonder what page talks about that?
> The Wiki mentions it is only required for older kernels - not the new ones.
> 
> 
> > immediately disappears; it doesn't even start to produce console
> 
> It probably was panicing b/c it couldn't swizzle out 64MB
> of DMA32 memory. You can find that out if you do 'earlyprintk=xenboot' and
> that should print out the bootlog in your Xen debug console (if you have
> configured guest_loglvl=all).
> 
> You can also do 'swiotlb=1024' to lower the amount. .. which should have worked,
> except that I found it does not work - so try this patch:
> 
> https://lkml.org/lkml/2011/6/1/554
> 
> Also, you can set this parameter in you guest file to analyze its stack:
> 
> on_crash="preserve"
> 
> using xenctx.
> 

xenctx usage is described here:
http://wiki.xen.org/xenwiki/XenCommonProblems#head-61843b32f0243b5ad0e17850f9493bffd80f8c17

-- Pasi