Re: [PATCH v1 2/9] RISC-V: drop a needless check in print_isa_ext()

From: Conor Dooley <conor@kernel.org>
To: Andrew Jones <ajones@ventanamicro.com>
Cc: devicetree@vger.kernel.org, Albert Ou <aou@eecs.berkeley.edu>,
	linux-kernel@vger.kernel.org,
	Conor Dooley <conor.dooley@microchip.com>,
	Rob Herring <robh+dt@kernel.org>,
	palmer@dabbelt.com,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	linux-riscv@lists.infradead.org,
	Heiko Stuebner <heiko.stuebner@vrull.eu>,
	Evan Green <evan@rivosinc.com>
Subject: Re: [PATCH v1 2/9] RISC-V: drop a needless check in print_isa_ext()
Date: Mon, 26 Jun 2023 17:08:28 +0100	[thread overview]
Message-ID: <20230626-jitters-spiral-68e941d0ad3f@spud> (raw)
In-Reply-To: <20230626-67e571e6d9f02c28a09dab33@orel>

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On Mon, Jun 26, 2023 at 05:19:08PM +0200, Andrew Jones wrote:
> On Mon, Jun 26, 2023 at 12:19:40PM +0100, Conor Dooley wrote:
> > isa_ext_arr cannot be empty, as some of the extensions within it are
> > always built into the kernel.
> 
> This is only true since commit 07edc32779e3 ("RISC-V: always report
> presence of extensions formerly part of the base ISA"), right? If
> so, it might be nice to call that commit out in this commit message.

Per my last mail, where I commented on the origins of some of this code,
there were no multi-letter extensions when this code was first added.
When the first multi-letter ones did get added, it was Sscofpmf - that
doesn't have a Kconfig symbol to disable it, so I think this has been
redundant for a long time.

Apart from the ones I recently added, there's a fair few others that
are not gated & should always be present.
It's probably not clear from the comment, but this check is for whether
the kernel supports extensions, not whether the system it is running on
does. I guess I should expand on that in my commit message.

Thanks,
Conor.

> > Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> > ---
> >  arch/riscv/kernel/cpu.c | 4 ----
> >  1 file changed, 4 deletions(-)
> > 
> > diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> > index 742bb42e7e86..01f7e5c62997 100644
> > --- a/arch/riscv/kernel/cpu.c
> > +++ b/arch/riscv/kernel/cpu.c
> > @@ -233,10 +233,6 @@ static void print_isa_ext(struct seq_file *f)
> >  
> >  	arr_sz = ARRAY_SIZE(isa_ext_arr) - 1;
> >  
> > -	/* No extension support available */
> > -	if (arr_sz <= 0)
> > -		return;
> > -
> >  	for (i = 0; i <= arr_sz; i++) {
> >  		edata = &isa_ext_arr[i];
> >  		if (!__riscv_isa_extension_available(NULL, edata->isa_ext_id))
> > -- 
> > 2.40.1
> >
> 
> Otherwise,
> 
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> 
> Thanks,
> drew

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