Re: [PATCH] bpf, docs: Add note about type convention

[David Vernet <void@manifault.com>]

On Fri, Jan 27, 2023 at 01:47:06AM +0000, dthaler1968@googlemail.com wrote:
> From: Dave Thaler <dthaler@microsoft.com>
> 
> Add explanation about use of "u64", "u32", etc. as
> the type convention used in BPF documentation.
> 
> Signed-off-by: Dave Thaler <dthaler@microsoft.com>

Acked-by: David Vernet <void@manifault.com>

> ---
> V2 -> V3: updated commit message to respond to David Vernet
> 
> V1 -> V2: addressed comments from Alexei and Stanislav
> by using u64 instead of uint64_t
> ---
>  Documentation/bpf/instruction-set.rst | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/instruction-set.rst
> index 2d3fe59bd26..77990c97b5e 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
>  ================================
> @@ -123,6 +128,8 @@ the destination register is unchanged whereas for ``BPF_ALU`` the upper
>  
>    dst_reg = (u32) dst_reg + (u32) src_reg;
>  
> +where '(u32)' indicates that the upper 32 bits are zeroed.
> +
>  ``BPF_ADD | BPF_X | BPF_ALU64`` means::
>  
>    dst_reg = dst_reg + src_reg
> -- 
> 2.33.4
>