Re: [dpdk-dev] [PATCH] doc: announce change in dma mapping/unmapping

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 8/25/2021 12:47 PM, Burakov, Anatoly wrote:
> On 25-Aug-21 12:27 PM, Xuan Ding wrote:
>> Currently, the VFIO subsystem will compact adjacent DMA regions for the
>> purposes of saving space in the internal list of mappings. This has a
>> side effect of compacting two separate mappings that just happen to be
>> adjacent in memory. Since VFIO implementation on IA platforms also does
>> not allow partial unmapping of memory mapped for DMA, the current DPDK
>> VFIO implementation will prevent unmapping of accidentally adjacent
>> maps even though it could have been unmapped [1].
>>
>> The proper fix for this issue is to change the VFIO DMA mapping API to
>> also include page size, and always map memory page-by-page.
>>
>> [1] https://mails.dpdk.org/archives/dev/2021-July/213493.html
>>
>> Signed-off-by: Xuan Ding <xuan.ding@intel.com>
>> ---
>>   doc/guides/rel_notes/deprecation.rst | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/doc/guides/rel_notes/deprecation.rst
>> b/doc/guides/rel_notes/deprecation.rst
>> index 76a4abfd6b..272ffa993e 100644
>> --- a/doc/guides/rel_notes/deprecation.rst
>> +++ b/doc/guides/rel_notes/deprecation.rst
>> @@ -287,3 +287,6 @@ Deprecation Notices
>>     reserved bytes to 2 (from 3), and use 1 byte to indicate warnings and other
>>     information from the crypto/security operation. This field will be used to
>>     communicate events such as soft expiry with IPsec in lookaside mode.
>> +
>> +  * vfio: the functions `rte_vfio_container_dma_map` and
>> `rte_vfio_container_dma_unmap`
>> +  will be amended to include page size. This change is targeted for DPDK 21.11.
>>
> 
> Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
> 

Techboard decision was to add a new API, instead of updating existing ones, to
not break the apps using this API.

@Xuan, @Anatoly, can you please confirm if this will solve your problem?