linux-kernel - Re: [PATCH v2] mips: smp-bmips: fix CPU mappings

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Date:   Sat, 27 Feb 2021 07:47:42 +0100
From:   Álvaro Fernández Rojas <noltari@...il.com>
To:     Jonas Gorski <jonas.gorski@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        bcm-kernel-feedback-list@...adcom.com, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mips: smp-bmips: fix CPU mappings

Hi all,

Apparently, this patch was flagged as "Not Applicable" without an explanation. Why?
https://patchwork.kernel.org/project/linux-mips/patch/20210224073336.32265-1-noltari@gmail.com/

Best regarss,
Álvaro.

> El 24 feb 2021, a las 8:33, Álvaro Fernández Rojas <noltari@...il.com> escribió:
> 
> When booting bmips with SMP enabled on a BCM6358 running on CPU #1 instead of
> CPU #0, the current CPU mapping code produces the following:
> - smp_processor_id(): 0
> - cpu_logical_map(0): 1
> - cpu_number_map(0): 1
> 
> This is because SMP isn't supported on BCM6358 since it has a shared TLB, so
> it is disabled and max_cpus is decreased from 2 to 1.
> 
> Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
> ---
> v2: Fix duplicated line
> 
> arch/mips/kernel/smp-bmips.c | 27 +++++++++++++++++----------
> 1 file changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/mips/kernel/smp-bmips.c b/arch/mips/kernel/smp-bmips.c
> index 359b176b665f..b6ef5f7312cf 100644
> --- a/arch/mips/kernel/smp-bmips.c
> +++ b/arch/mips/kernel/smp-bmips.c
> @@ -134,17 +134,24 @@ static void __init bmips_smp_setup(void)
> 	if (!board_ebase_setup)
> 		board_ebase_setup = &bmips_ebase_setup;
> 
> -	__cpu_number_map[boot_cpu] = 0;
> -	__cpu_logical_map[0] = boot_cpu;
> -
> -	for (i = 0; i < max_cpus; i++) {
> -		if (i != boot_cpu) {
> -			__cpu_number_map[i] = cpu;
> -			__cpu_logical_map[cpu] = i;
> -			cpu++;
> +	if (max_cpus > 1) {
> +		__cpu_number_map[boot_cpu] = 0;
> +		__cpu_logical_map[0] = boot_cpu;
> +
> +		for (i = 0; i < max_cpus; i++) {
> +			if (i != boot_cpu) {
> +				__cpu_number_map[i] = cpu;
> +				__cpu_logical_map[cpu] = i;
> +				cpu++;
> +			}
> +			set_cpu_possible(i, 1);
> +			set_cpu_present(i, 1);
> 		}
> -		set_cpu_possible(i, 1);
> -		set_cpu_present(i, 1);
> +	} else {
> +		__cpu_number_map[0] = boot_cpu;
> +		__cpu_logical_map[0] = 0;
> +		set_cpu_possible(0, 1);
> +		set_cpu_present(0, 1);
> 	}
> }
> 
> -- 
> 2.20.1
>