From: Segher Boessenkool <segher@kernel.crashing.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, libc-alpha@sourceware.org,
gcc@gcc.gnu.org, Paul E Murphy <murphyp@linux.ibm.com>,
Peter Bergner <bergner@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH v2] powerpc: add documentation for HWCAPs
Date: Fri, 15 Jul 2022 09:57:17 -0500 [thread overview]
Message-ID: <20220715145717.GZ25951@gate.crashing.org> (raw)
In-Reply-To: <20220715012636.165948-1-npiggin@gmail.com>
On Fri, Jul 15, 2022 at 11:26:36AM +1000, Nicholas Piggin wrote:
> Take the arm64 HWCAP documentation file and adjust it for powerpc.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
> +2. Facilities
> +-------------
> +
> +The Power ISA uses the term "facility" to describe a class of instructions,
> +registers, interrupts, etc. The presence or absence of a facility indicates
> +whether this class is available to be used, but the specifics depend on the
> +ISA version. For example, if the VSX facility is available, the VSX
> +instructions that can be used differ between the v3.0B and v3.1B ISA
> +versions.
The term "facility" is never defined in the architecture documents, so
the common language meaning applies, which google says is "a place,
amenity, or piece of equipment provided for a particular purpose", which
fits your explanation well.
> +3. Categories
> +-------------
> +
> +The Power ISA before v3.0 uses the term "category" to describe certain
> +classes of instructions and operating modes which may be optional or
> +mutually exclusive, the exact meaning of the HWCAP flag may depend on
> +context, e.g., the presence of the BOOKE feature implies that the server
> +category is not implemented.
Since ISA 3.0 the preface says
The resulting architecture included [...] and optional application-
specific facilities (categories) as extensions to a pervasive base
architecture.
which fits your explanation.
Thanks for improving the documentation!
Segher
next prev parent reply other threads:[~2022-07-15 14:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-15 1:26 Nicholas Piggin
2022-07-15 14:57 ` Segher Boessenkool [this message]
2022-07-15 18:41 ` Tulio Magno Quites Machado Filho
2022-07-15 19:59 ` Segher Boessenkool
2022-07-15 20:17 ` Tulio Magno Quites Machado Filho
2022-07-20 9:28 ` Nicholas Piggin
2022-07-29 13:02 ` Michael Ellerman
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