From: Evan Green <evan@rivosinc.com>
To: "Clément Léger" <cleger@rivosinc.com>
Cc: Jerry Shih <jerry.shih@sifive.com>,
linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
Palmer Dabbelt <palmer@rivosinc.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Albert Ou <aou@eecs.berkeley.edu>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Jones <ajones@ventanamicro.com>,
Conor Dooley <conor@kernel.org>,
Samuel Ortiz <sameo@rivosinc.com>
Subject: Re: [PATCH v2 05/19] riscv: add ISA extension parsing for vector crypto extensions
Date: Wed, 18 Oct 2023 10:26:34 -0700 [thread overview]
Message-ID: <CALs-HstEBt-ntCcETa9YwS6On3nGyoEc2p7R-gaBLG9+aFJL5w@mail.gmail.com> (raw)
In-Reply-To: <af785f0f-9de7-4548-9cdb-f392cde1cc2b@rivosinc.com>
On Wed, Oct 18, 2023 at 5:53 AM Clément Léger <cleger@rivosinc.com> wrote:
>
>
>
> On 18/10/2023 03:45, Jerry Shih wrote:
> > On Oct 17, 2023, at 21:14, Clément Léger <cleger@rivosinc.com> wrote:
> >> @@ -221,6 +261,22 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
> >> __RISCV_ISA_EXT_DATA(zkt, RISCV_ISA_EXT_ZKT),
> >> __RISCV_ISA_EXT_DATA(zksed, RISCV_ISA_EXT_ZKSED),
> >> __RISCV_ISA_EXT_DATA(zksh, RISCV_ISA_EXT_ZKSH),
> >> + __RISCV_ISA_EXT_DATA(zvbb, RISCV_ISA_EXT_ZVBB),
> >> + __RISCV_ISA_EXT_DATA(zvbc, RISCV_ISA_EXT_ZVBC),
> >> + __RISCV_ISA_EXT_DATA(zvkb, RISCV_ISA_EXT_ZVKB),
> >
> > The `Zvkb` is the subset of `Zvbb`[1]. So, the `Zvkb` should be bundled with `Zvbb`.
>
> Hi Jerry,
>
> Thanks for catching this, I think some other extensions will fall in
> this category as well then (Zvknha/Zvknhb). I will verify that.
The bundling mechanism works well when an extension is a pure lasso
around other extensions. We'd have to tweak that code if we wanted to
support cases like this, where the extension is a superset of others,
but also contains loose change not present anywhere else (and
therefore also needs to stand as a separate bit).
IMO, decomposing "pure" bundles makes sense since otherwise usermode
would have to query multiple distinct bitmaps that meant the same
thing (eg check the Zk bit, or maybe check the Zkn/Zkr/Zkt bits, or
maybe check the Zbkb/Zbkc... bits, and they're all equivalent). But
when an extension is a superset that also contains loose change, there
really aren't two equivalent bitmasks, each bit adds something new.
There's an argument to be made for still turning on the containing
extensions to cover for silly ISA strings (eg ISA strings that
advertise the superset but fail to advertise the containing
extensions). We can decide if we want to work that hard to cover
hypothetical broken ISA strings now, or wait until they show up.
Personally I would wait until something broken shows up. But others
may feel differently.
-Evan
next prev parent reply other threads:[~2023-10-18 17:27 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-17 13:14 [PATCH v2 00/19] riscv: report more ISA extensions through hwprobe Clément Léger
2023-10-17 13:14 ` [PATCH v2 01/19] riscv: hwprobe: factorize hwprobe ISA extension reporting Clément Léger
2023-10-18 17:24 ` Evan Green
2023-10-18 17:33 ` Conor Dooley
2023-10-18 17:36 ` Conor Dooley
2023-10-18 17:45 ` Evan Green
2023-10-19 9:46 ` Clément Léger
2023-10-19 10:24 ` Conor Dooley
2023-10-19 15:58 ` Evan Green
2023-10-19 7:26 ` Clément Léger
2023-10-19 10:22 ` Conor Dooley
2023-10-19 12:29 ` Clément Léger
2023-10-20 10:27 ` Andrew Jones
2023-10-17 13:14 ` [PATCH v2 02/19] riscv: add ISA extension parsing for scalar crypto Clément Léger
2023-10-23 16:21 ` Evan Green
2023-10-24 7:18 ` Clément Léger
2023-10-24 9:30 ` Clément Léger
2023-10-24 16:37 ` Evan Green
2023-10-24 18:11 ` Clément Léger
2023-10-17 13:14 ` [PATCH v2 03/19] riscv: hwprobe: add support for scalar crypto ISA extensions Clément Léger
2023-10-18 17:24 ` Evan Green
2023-10-19 7:21 ` Clément Léger
2023-10-17 13:14 ` [PATCH v2 04/19] dt-bindings: riscv: add scalar crypto ISA extensions description Clément Léger
2023-10-17 13:14 ` [PATCH v2 05/19] riscv: add ISA extension parsing for vector crypto extensions Clément Léger
2023-10-18 1:45 ` Jerry Shih
2023-10-18 12:52 ` Clément Léger
2023-10-18 17:26 ` Evan Green [this message]
2023-10-19 9:35 ` Clément Léger
2023-10-19 15:33 ` Conor Dooley
2023-10-19 16:19 ` Evan Green
2023-10-23 7:24 ` Clément Léger
2023-10-23 16:18 ` Evan Green
2023-10-20 2:43 ` Jerry Shih
2023-10-23 7:14 ` Clément Léger
2023-10-17 13:14 ` [PATCH v2 06/19] riscv: hwprobe: export vector crypto ISA extensions Clément Léger
2023-10-18 17:27 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 07/19] dt-bindings: riscv: add vector crypto ISA extensions description Clément Léger
2023-10-17 13:14 ` [PATCH v2 08/19] riscv: add ISA extension parsing for Zfh/Zfhmin Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 09/19] riscv: hwprobe: export Zfh/Zfhmin ISA extensions Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 10/19] dt-bindings: riscv: add Zfh[min] ISA extensions description Clément Léger
2023-10-17 13:14 ` [PATCH v2 11/19] riscv: add ISA extension parsing for Zihintntl Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 12/19] riscv: hwprobe: export Zhintntl ISA extension Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 13/19] dt-bindings: riscv: add Zihintntl ISA extension description Clément Léger
2023-10-17 13:14 ` [PATCH v2 14/19] riscv: add ISA extension parsing for Zvfh[min] Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 15/19] riscv: hwprobe: export Zvfh[min] ISA extensions Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 16/19] dt-bindings: riscv: add Zvfh[min] ISA extension description Clément Léger
2023-10-17 13:14 ` [PATCH v2 17/19] riscv: add ISA extension parsing for Zfa Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 18/19] riscv: hwprobe: export Zfa ISA extension Clément Léger
2023-10-18 17:28 ` Evan Green
2023-10-17 13:14 ` [PATCH v2 19/19] dt-bindings: riscv: add Zfa ISA extension description Clément Léger
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