diff mbox series

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

Message ID 20230626-skydiver-frown-659b982a43ad@wendy
State New
Headers
Series RISC-V: Probe DT extension support using riscv,isa-extensions & riscv,isa-base |

Commit Message

Conor Dooley June 26, 2023, 11:19 a.m. UTC 
  isa_ext_arr cannot be empty, as some of the extensions within it are
always built into the kernel.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
 arch/riscv/kernel/cpu.c | 4 ----
 1 file changed, 4 deletions(-)

Comments

Andrew Jones June 26, 2023, 3:19 p.m. UTC | #1 
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.

> 
> 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
Conor Dooley June 26, 2023, 4:08 p.m. UTC | #2 
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
Andrew Jones June 26, 2023, 4:29 p.m. UTC | #3 
On Mon, Jun 26, 2023 at 05:08:28PM +0100, Conor Dooley wrote:
> 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.

That part I understood, but I was thinking it'd be nice to call out when
the first extension was added which cannot be disabled by a config to
provide extra evidence that it's safe to remove the check.

Thanks,
drew
diff mbox series

Patch

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))