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* [dpdk-dev] [PATCH] doc: announce change in dma mapping/unmapping
@ 2021-08-25 11:27 Xuan Ding
  2021-08-25 11:47 ` Burakov, Anatoly
  0 siblings, 1 reply; 7+ messages in thread
From: Xuan Ding @ 2021-08-25 11:27 UTC (permalink / raw)
  To: dev, anatoly.burakov, maxime.coquelin, chenbo.xia
  Cc: ferruh.yigit, jiayu.hu, bruce.richardson, Xuan Ding

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.
-- 
2.17.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-08-31 13:42 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-25 11:27 [dpdk-dev] [PATCH] doc: announce change in dma mapping/unmapping Xuan Ding
2021-08-25 11:47 ` Burakov, Anatoly
2021-08-26  9:29   ` Ferruh Yigit
2021-08-26  9:46     ` Burakov, Anatoly
2021-08-26 10:09       ` Bruce Richardson
2021-08-26 10:14         ` Burakov, Anatoly
2021-08-31 13:42           ` Ding, Xuan

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