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Date: Tue, 7 May 2024 13:39:14 -0700
From: Charlie Jenkins <charlie@rivosinc.com>
To: Jessica Clarke <jrtc27@jrtc27.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Conor Dooley <conor.dooley@microchip.com>,
	Song Liu <song@kernel.org>, Xi Wang <xi.wang@gmail.com>,
	=?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn@rivosinc.com>,
	=?iso-8859-1?Q?Cl=E9ment_L=E9ger?= <cleger@rivosinc.com>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/8] riscv: Add PLATFORM_MAY_SUPPORT_RISCV_ISA_SVPBMT
 Kconfig option
Message-ID: <ZjqRcsheypWX14yy@ghost>
References: <20240506-compile_kernel_with_extensions-v1-0-5c25c134c097@rivosinc.com>
 <20240506-compile_kernel_with_extensions-v1-4-5c25c134c097@rivosinc.com>
 <11F5B269-05DD-448E-9F85-878E84A5654F@jrtc27.com>
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In-Reply-To: <11F5B269-05DD-448E-9F85-878E84A5654F@jrtc27.com>

On Tue, May 07, 2024 at 06:40:52AM +0100, Jessica Clarke wrote:
> On 7 May 2024, at 02:40, Charlie Jenkins <charlie@rivosinc.com> wrote:
> > 
> > Svpbmt would not benefit from having PLATFORM_SUPPORTS_RISCV_ISA_SVPBMT
> > so just rename RISCV_ISA_SVPBMT to PLATFORM_MAY_SUPPORT_RISCV_ISA_SVPBMT
> > and move the definition to Kconfig.isa.
> > 
> > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> > ---
> > arch/riscv/Kconfig     | 17 -----------------
> > arch/riscv/Kconfig.isa | 17 +++++++++++++++++
> > 2 files changed, 17 insertions(+), 17 deletions(-)
> > 
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 9c3a4347953b..22303a3ab59e 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -484,23 +484,6 @@ config RISCV_ALTERNATIVE_EARLY
> > help
> >  Allows early patching of the kernel for special errata
> > 
> > -config RISCV_ISA_SVPBMT
> > - bool "Svpbmt extension support for supervisor mode page-based memory types"
> > - depends on 64BIT && MMU
> > - depends on RISCV_ALTERNATIVE
> > - default y
> > - help
> > -   Add support for the Svpbmt ISA-extension (Supervisor-mode:
> > -   page-based memory types) in the kernel when it is detected at boot.
> > -
> > -   The memory type for a page contains a combination of attributes
> > -   that indicate the cacheability, idempotency, and ordering
> > -   properties for access to that page.
> > -
> > -   The Svpbmt extension is only available on 64-bit cpus.
> > -
> > -   If you don't know what to do here, say Y.
> > -
> > config TOOLCHAIN_HAS_ZBB
> > bool
> > default y
> > diff --git a/arch/riscv/Kconfig.isa b/arch/riscv/Kconfig.isa
> > index 37585bcd763e..50e217dc5719 100644
> > --- a/arch/riscv/Kconfig.isa
> > +++ b/arch/riscv/Kconfig.isa
> > @@ -168,3 +168,20 @@ config PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT
> >  not support Svnapot.
> > 
> > endchoice
> > +
> > +config RISCV_ISA_SVPBMT
> 
> Hi Charlie,
> Despite the subject and body you haven’t renamed it in this patch?

I didn't do a good job at explaining exactly what's happening here. The
config option "PLATFORM_MAY_SUPPORT_RISCV_ISA_SVPBMT" most closely
follows the semantics of what "RISCV_ISA_SVPBMT" previously was. This
patch changes "RISCV_ISA_SVPBMT" to mean that either
PLATFORM_MAY_SUPPORT_RISCV_ISA_SVPBMT or
PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT was selected.

- Charlie

> 
> Jess
> 
> > + bool "Svpbmt extension support for supervisor mode page-based memory types"
> > + depends on 64BIT && MMU
> > + depends on RISCV_ALTERNATIVE
> > + default y
> > + help
> > +   Add support for the Svpbmt ISA-extension (Supervisor-mode:
> > +   page-based memory types) in the kernel when it is detected at boot.
> > +
> > +   The memory type for a page contains a combination of attributes
> > +   that indicate the cacheability, idempotency, and ordering
> > +   properties for access to that page.
> > +
> > +   The Svpbmt extension is only available on 64-bit cpus.
> > +
> > +   If you don't know what to do here, say Y.
> > 
> > -- 
> > 2.44.0
> > 
> > 
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>