From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: Status of "dma, x86,
 xen: reduce SWIOTLB usage in Xen guests" series
Date: Mon, 25 Jan 2016 10:47:18 +0000
Message-ID: <56A5FD36.5030903@citrix.com>
References: <56A3FAD2.3020506@prgmr.com>
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To: Sarah Newman <srn@prgmr.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
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On 23/01/16 22:12, Sarah Newman wrote:
> Greetings,
> 
> We are having problems related to mptsas and "swiotlb buffer is full" with the Xen4CentOS kernel (3.18). It looks like the last related work was
> the series http://lists.xenproject.org/archives/html/xen-devel/2014-12/msg00770.html back at the end of 2014 and I'm wondering if there are any plans
> to revive the series.

I should try and revive it...

> The error with swiotlb has caused us a massive amount of problems. We set swiotlb=32768 on one server and are still seeing this error message on
> occasion. If there's anything I can do to help please let me know.

As a workaround, you can give dom0 more than 4 GiB and then the driver
will set a 64-bit DMA mask.  I don't think the memory needs to populated
so something like dom0_mem=2GiB,max:4GiB might work.

David