diff options
Diffstat (limited to 'Documentation/ntb.txt')
| -rw-r--r-- | Documentation/ntb.txt | 14 |
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 |