linux-kernel - Re: [PATCH v4 06/11] dt-bindings: riscv: Add B ISA extension description

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAH1PCMYgGVm1uJMjoxVkOMvPeRLsvybi7PW9k3sWyj3ij8c4Vg@mail.gmail.com>
Date: Tue, 13 Jan 2026 10:44:31 +0800
From: Guodong Xu <guodong@...cstar.com>
To: Conor Dooley <conor@...nel.org>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Paul Walmsley <pjw@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, Yixun Lan <dlan@...too.org>, 
	Daniel Lezcano <daniel.lezcano@...aro.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Samuel Holland <samuel.holland@...ive.com>, Anup Patel <anup@...infault.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Lubomir Rintel <lkundrak@...sk>, Yangyu Chen <cyy@...self.name>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Heinrich Schuchardt <xypron.glpk@....de>, 
	Kevin Meng Zhang <zhangmeng.kevin@...ux.spacemit.com>, Andrew Jones <ajones@...tanamicro.com>, 
	devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, spacemit@...ts.linux.dev, 
	linux-serial@...r.kernel.org
Subject: Re: [PATCH v4 06/11] dt-bindings: riscv: Add B ISA extension description

Hi, Conor

On Tue, Jan 13, 2026 at 5:41 AM Conor Dooley <conor@...nel.org> wrote:
>
> On Sat, Jan 10, 2026 at 01:18:18PM +0800, Guodong Xu wrote:
> > Add description of the single-letter B extension for Bit Manipulation.
> > B is mandatory for RVA23U64.
> >
> > The B extension is ratified in the 20240411 version of the unprivileged
> > ISA specification. According to the ratified spec, the B standard
> > extension comprises instructions provided by the Zba, Zbb, and Zbs
> > extensions.
> >
> > Add two-way dependency check to enforce that B implies Zba/Zbb/Zbs; and
> > when Zba/Zbb/Zbs (all of them) are specified, then B must be added too.
> >
> > The reason why B/Zba/Zbb/Zbs must coexist at the same time is that
> > unlike other single-letter extensions, B was ratified (Apr/2024) much
> > later than its component extensions Zba/Zbb/Zbs (Jun/2021).
> >
> > When "b" is specified, zba/zbb/zbs must be present to ensure
> > backward compatibility with existing software and kernels that only
> > look for the explicit component strings.
> >
> > When all three components zba/zbb/zbs are specified, "b" should also be
> > present. Making "b" mandatory when all three components are present.
>
> > Existing devicetrees with zba/zbb/zbs but without "b" will generate
> > warnings that can be fixed in follow-up patches.
>
> Are you going to send these fixup patches for other devicetrees? The
> majority appear to be other spacemit devices.

Yes, I will. My check shows that these three dtsi files need to be updated to
include the newly ratified "b" extension:

arch/riscv/boot/dts/anlogic/dr1v90.dtsi
arch/riscv/boot/dts/sophgo/sg2044-cpus.dtsi
arch/riscv/boot/dts/spacemit/k1.dtsi

I will start a follow up patch to update these dtsi files. Basically, adding
"b" into both the "riscv,isa-extensions" and "riscv,isa" (when available)
fields.

Thank you for your review.

Best regards,
Guodong Xu