From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jambunathan K <jambunathan@netxen.com>
Subject: Re: xen_create_contiguous_region  - Regarding
Date: Mon, 09 Apr 2007 18:47:36 +0530
Message-ID: <461A3CF0.7020406@netxen.com>
References: <C23BE869.580E%Keir.Fraser@cl.cam.ac.uk>
	<4616430F.2030507@netxen.com>
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To: Jambunathan K <jambunathan@netxen.com>
Cc: xen-devel@lists.xensource.com, sanjeev@netxen.com
List-Id: xen-devel@lists.xenproject.org

Given that our driver supports 35-bit mask, the fact that
xen_create_contiguous_region constrains "machine contiguous" allocations
to less than dma_bits seems very limiting.

What would be the recommended way to get machine contiguous pages within
 say (1<<35)?

Regards,
Jambunathan K.


Jambunathan K wrote:
>>> pci_map_single() will do what you want automatically. If you really want to
>>> allocate contiguous memory yourself, allocate it then call
>>> xen_create_contiguous_region().
> 
> Could you please export xen_create_contiguous_region for wider use?
> 
> Jambunathan K.
> 
> 
> Keir Fraser wrote:
>> On 6/4/07 11:46, "Jambunathan K" <jambunathan@netxen.com> wrote:
>>
>>> Given that we prefer to maintain our own bounce buffers, I could neither
>>> find a dependable API that let the driver allocate machine contiguous
>>> memory (that could later be *pci_map_singled*) nor find a suitable hook
>>> to xen_create_contiguous_region.
>> pci_map_single() will do what you want automatically. If you really want to
>> allocate contiguous memory yourself, allocate it then call
>> xen_create_contiguous_region().
>>
>>> As an aside, is there a tweak to "increase" contiguous memory regions
>>> available so that xen_create_contiguous_regions() succeeds. On DomUs,
>>> when swiotlb is enabled, I see some crashes which I would like to avoid
>>> by redistributing memory resources.
>> Xen will try to maintain contiguity as far as possible, but it cannot
>> defragment the memory map.
>>
>>  -- Keir
>>
>>
>>
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>>
> 
>