[bpf-next,v5,11/11] doc/af_xdp: include unaligned chunk case
diff mbox series

Message ID 20190822014427.49800-12-kevin.laatz@intel.com
State Superseded
Delegated to: BPF Maintainers
Headers show
Series
  • XDP unaligned chunk placement support
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Commit Message

Laatz, Kevin Aug. 22, 2019, 1:44 a.m. UTC
The addition of unaligned chunks mode, the documentation needs to be
updated to indicate that the incoming addr to the fill ring will only be
masked if the user application is run in the aligned chunk mode. This patch
also adds a line to explicitly indicate that the incoming addr will not be
masked if running the user application in the unaligned chunk mode.

Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
---
 Documentation/networking/af_xdp.rst | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Patch
diff mbox series

diff --git a/Documentation/networking/af_xdp.rst b/Documentation/networking/af_xdp.rst
index eeedc2e826aa..83f7ae5fc045 100644
--- a/Documentation/networking/af_xdp.rst
+++ b/Documentation/networking/af_xdp.rst
@@ -153,10 +153,12 @@  an example, if the UMEM is 64k and each chunk is 4k, then the UMEM has
 
 Frames passed to the kernel are used for the ingress path (RX rings).
 
-The user application produces UMEM addrs to this ring. Note that the
-kernel will mask the incoming addr. E.g. for a chunk size of 2k, the
-log2(2048) LSB of the addr will be masked off, meaning that 2048, 2050
-and 3000 refers to the same chunk.
+The user application produces UMEM addrs to this ring. Note that, if
+running the application with aligned chunk mode, the kernel will mask
+the incoming addr.  E.g. for a chunk size of 2k, the log2(2048) LSB of
+the addr will be masked off, meaning that 2048, 2050 and 3000 refers
+to the same chunk. If the user application is run in the unaligned
+chunks mode, then the incoming addr will be left untouched.
 
 
 UMEM Completion Ring