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[1/4] bpf, docs: Add note about type convention

Message ID 20221019183845.905-1-dthaler1968@googlemail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series [1/4] bpf, docs: Add note about type convention | expand

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Commit Message

Dave Thaler Oct. 19, 2022, 6:38 p.m. UTC 
From: Dave Thaler <dthaler@microsoft.com>

Add note about type convention

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
---
 Documentation/bpf/instruction-set.rst | 7 +++++++
 1 file changed, 7 insertions(+)
diff mbox series

Patch

diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
index 4997d2088..6847a4cbf 100644
--- a/Documentation/bpf/instruction-set.rst
+++ b/Documentation/bpf/instruction-set.rst
@@ -7,6 +7,11 @@  eBPF Instruction Set Specification, v1.0
 
 This document specifies version 1.0 of the eBPF instruction set.
 
+Documentation conventions
+=========================
+
+For brevity, this document uses the type notion "u64", "u32", etc.
+to mean an unsigned integer whose width is the specified number of bits.
 
 Registers and calling convention
 ================================
@@ -116,6 +121,8 @@  BPF_END   0xd0   byte swap operations (see `Byte swap instructions`_ below)
 
   dst_reg = (u32) dst_reg + (u32) src_reg;
 
+where '(u32)' indicates truncation to 32 bits.
+
 ``BPF_ADD | BPF_X | BPF_ALU64`` means::
 
   dst_reg = dst_reg + src_reg