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authorLinus Torvalds <torvalds@linux-foundation.org>2019-05-08 12:42:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-05-08 12:42:50 -0700
commit8c79f4cd441b27df6cadd11b70a50e06b3b3a2bf (patch)
tree0d7fca2a5fb43fa75b51c4cdaaee493e44d56d62 /Documentation/ntb.txt
parent2646719a48c21ba0cae82a3f57382a9573fd8400 (diff)
parentd9defe448f4c7b88ca2ae636a321ef8970fa718d (diff)
Merge tag 'docs-5.2' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet: "A reasonably busy cycle for docs, including: - Lots of work on the Chinese and Italian translations - Some license-rules clarifications from Christoph - Various build-script fixes - A new document on memory models - RST conversion of the live-patching docs - The usual collection of typo fixes and corrections" * tag 'docs-5.2' of git://git.lwn.net/linux: (140 commits) docs/livepatch: Unify style of livepatch documentation in the ReST format docs: livepatch: convert docs to ReST and rename to *.rst scripts/documentation-file-ref-check: detect broken :doc:`foo` scripts/documentation-file-ref-check: don't parse Next/ dir LICENSES: Rename other to deprecated LICENSES: Clearly mark dual license only licenses docs: Don't reference the ZLib license in license-rules.rst docs/vm: Minor editorial changes in the THP and hugetlbfs docs/vm: add documentation of memory models doc:it_IT: translation alignment doc: fix typo in PGP guide dontdiff: update with Kconfig build artifacts docs/zh_CN: fix typos in 1.Intro.rst file docs/zh_CN: redirect CoC docs to Chinese version doc: mm: migration doesn't use FOLL_SPLIT anymore docs: doc-guide: remove the extension from .rst files doc: kselftest: Fix KBUILD_OUTPUT usage instructions docs: trace: fix some Sphinx warnings docs: speculation.txt: mark example blocks as such docs: ntb.txt: add blank lines to clean up some Sphinx warnings ...
Diffstat (limited to 'Documentation/ntb.txt')
-rw-r--r--Documentation/ntb.txt14
1 files changed, 10 insertions, 4 deletions
diff --git a/Documentation/ntb.txt b/Documentation/ntb.txt
index a043854d28df..074a423c853c 100644
--- a/Documentation/ntb.txt
+++ b/Documentation/ntb.txt
@@ -41,9 +41,10 @@ mainly used to perform the proper memory window initialization. Typically
there are two types of memory window interfaces supported by the NTB API:
inbound translation configured on the local ntb port and outbound translation
configured by the peer, on the peer ntb port. The first type is
-depicted on the next figure
+depicted on the next figure::
+
+ Inbound translation:
-Inbound translation:
Memory: Local NTB Port: Peer NTB Port: Peer MMIO:
____________
| dma-mapped |-ntb_mw_set_trans(addr) |
@@ -58,9 +59,10 @@ maps corresponding outbound memory window so to have access to the shared
memory region.
The second type of interface, that implies the shared windows being
-initialized by a peer device, is depicted on the figure:
+initialized by a peer device, is depicted on the figure::
+
+ Outbound translation:
-Outbound translation:
Memory: Local NTB Port: Peer NTB Port: Peer MMIO:
____________ ______________
| dma-mapped | | | MW base addr |<== memory-mapped IO
@@ -75,11 +77,13 @@ outbound memory window so to have access to the shared memory region.
As one can see the described scenarios can be combined in one portable
algorithm.
+
Local device:
1) Allocate memory for a shared window
2) Initialize memory window by translated address of the allocated region
(it may fail if local memory window initialization is unsupported)
3) Send the translated address and memory window index to a peer device
+
Peer device:
1) Initialize memory window with retrieved address of the allocated
by another device memory region (it may fail if peer memory window
@@ -88,6 +92,7 @@ algorithm.
In accordance with this scenario, the NTB Memory Window API can be used as
follows:
+
Local device:
1) ntb_mw_count(pidx) - retrieve number of memory ranges, which can
be allocated for memory windows between local device and peer device
@@ -103,6 +108,7 @@ follows:
5) Send translated base address (usually together with memory window
number) to the peer device using, for instance, scratchpad or message
registers.
+
Peer device:
1) ntb_peer_mw_set_trans(pidx, midx) - try to set received from other
device (related to pidx) translated address for specified memory