From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH v2 19/21] xen/arm: Reserve region in guest
 memory for device passthrough
Date: Wed, 06 Aug 2014 17:33:04 +0100
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xenproject.org, tim@xen.org, ian.campbell@citrix.com, stefano.stabellini@citrix.com
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Hi Stefano,

On 08/06/2014 05:27 PM, Stefano Stabellini wrote:
> On Thu, 31 Jul 2014, Julien Grall wrote:
>> This region will be split by the toolstack to allocate MMIO range for eac
>> device.
>>
>> For now only reserve a 768MB region, this should be enought to passthrough
>> multiple device at the same time.
>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>>
>> ---
>>
>> I can't allocate easily a range of 1GB in the current layout without shrink
>> the first RAM bank. So I decided to use only 768MB. If in the future we need
>> more, then we will have to choose at runtime the guest layout.
>>
>>     Changes in v2:
>>         - Bump the reserved region from 512MB to 768MB
> 
> 
> Better than nothing.
> Would it be possible to add a second region > 4GB? Maybe after RAM?
> How hard would be to handle that?

It won't work if the guest is using short-descriptor translation table
format because only 32 bits address will be supported.

Regards,

-- 
Julien Grall