Thank you for the feedback! Responses inline.
On Tue, Aug 1, 2023 at 3:35 PM David Vernet <void@xxxxxxxxxxxxx> wrote:
>
> On Sat, Jul 29, 2023 at 11:51:56PM -0400, Will Hawkins wrote:
> > Give a single place where the shorthand for types are defined and the
> > semantics of helper functions are described.
> >
> > Signed-off-by: Will Hawkins <hawkinsw@xxxxxx>
> > ---
> > .../bpf/standardization/instruction-set.rst | 65 ++++++++++++++++++-
> > Documentation/sphinx/requirements.txt | 2 +-
> > 2 files changed, 63 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/bpf/standardization/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst
> > index fb8154cedd84..97378388e20b 100644
> > --- a/Documentation/bpf/standardization/instruction-set.rst
> > +++ b/Documentation/bpf/standardization/instruction-set.rst
> > @@ -10,9 +10,68 @@ 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,
> > -and "s32", etc. to mean a signed integer of the specified number of bits.
> > +For brevity and consistency, this document refers to families
> > +of types using a shorthand syntax and refers to several helper
> > +functions when explaining the semantics of opcodes. The range
>
> nit: Can we use a different term than "helper functions" here, just
> because it's an overloaded term for BPF. Maybe "shorthand functions" or
> "mnemonic functions"? Or just "functions"?
Great idea. I like the term mnemonic functions (given that we talk
about mnemonics with opcodes). I will go with that unless there is
additional guidance.
>
> > +of valid values for those types and the semantics of those functions
> > +are defined in the following subsections.
> > +
> > +Types
> > +-----
> > +This document refers to integer types with a notation of the form `SX`
>
> I suggest replacing `SX` with `Sn`, as `SX` is short for sign-extension
> in several instructions.
Good point! Will do!
>
> > +that succinctly defines whether their values are signed or unsigned
> > +numbers and the bit widths:
> > +
> > +=== =======
> > +`S` Meaning
> > +=== =======
> > +`u` unsigned
> > +`s` signed
> > +=== =======
> > +
> > +===== =========
> > +`X` Bit width
> > +===== =========
> > +`8` 8 bits
> > +`16` 16 bits
> > +`32` 32 bits
> > +`64` 64 bits
> > +`128` 128 bits
> > +===== =========
> > +
> > +For example, `u32` is a type whose valid values are all the 32-bit unsigned
> > +numbers and `s16` is a types whose valid values are all the 16-bit signed
> > +numbers.
> > +
> > +Functions
> > +---------
> > +* `htobe16`: Takes an unsigned 16-bit number in host-endian format and
> > + returns the equivalent number as an unsigned 16-bit number in big-endian
> > + format.
> > +* `htobe32`: Takes an unsigned 32-bit number in host-endian format and
> > + returns the equivalent number as an unsigned 32-bit number in big-endian
> > + format.
> > +* `htobe64`: Takes an unsigned 64-bit number in host-endian format and
> > + returns the equivalent number as an unsigned 64-bit number in big-endian
> > + format.
> > +* `htole16`: Takes an unsigned 16-bit number in host-endian format and
> > + returns the equivalent number as an unsigned 16-bit number in little-endian
> > + format.
> > +* `htole32`: Takes an unsigned 32-bit number in host-endian format and
> > + returns the equivalent number as an unsigned 32-bit number in little-endian
> > + format.
> > +* `htole64`: Takes an unsigned 64-bit number in host-endian format and
> > + returns the equivalent number as an unsigned 64-bit number in little-endian
> > + format.
>
> Hmm, some of these functions aren't actually used elsewhere in the
> document. Maybe update the hto{b,l}eN examples later in the Byte swap
> instructions section to match bswapN where all widths are illustrated in
> the example?
>
Another great point. Will do!
> > +* `bswap16`: Takes an unsigned 16-bit number in either big- or little-endian
> > + format and returns the equivalent number with the same bit width but
> > + opposite endianness.
> > +* `bswap32`: Takes an unsigned 32-bit number in either big- or little-endian
> > + format and returns the equivalent number with the same bit width but
> > + opposite endianness.
> > +* `bswap64`: Takes an unsigned 64-bit number in either big- or little-endian
> > + format and returns the equivalent number with the same bit width but
> > + opposite endianness.
> >
> > Registers and calling convention
> > ================================
> > diff --git a/Documentation/sphinx/requirements.txt b/Documentation/sphinx/requirements.txt
> > index 335b53df35e2..9479c5c2e338 100644
> > --- a/Documentation/sphinx/requirements.txt
> > +++ b/Documentation/sphinx/requirements.txt
> > @@ -1,3 +1,3 @@
> > # jinja2>=3.1 is not compatible with Sphinx<4.0
> > jinja2<3.1
> > -Sphinx==2.4.4
> > +Sphinx==7.1.1
>
> I don't think we can unilaterally update the whole kernel docs tree to
> require a new version of Sphinx like this. Could you please clarify why
> you needed to update it? Was it for the tables or something?
An absolute git typo on my part. I will remove in v2.
Thanks again for the feedback!
Will
>
> > --
> > 2.40.1
> >
> > --
> > Bpf mailing list
> > Bpf@xxxxxxxx
> > https://www.ietf.org/mailman/listinfo/bpf
