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From: John Ogness <john.ogness@linutronix.de>
To: Luis Chamberlain <mcgrof@kernel.org>, Yoann Congal
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Subject: Re: [PATCH v2] printk: Remove redundant CONFIG_BASE_SMALL
In-Reply-To: <ZbfLl6PR_qxxreeX@bombadil.infradead.org>
References: <20240127220026.1722399-1-yoann.congal@smile.fr>
 <ZbfLl6PR_qxxreeX@bombadil.infradead.org>
Date: Wed, 31 Jan 2024 16:53:32 +0106
Message-ID: <871q9xzeqz.fsf@jogness.linutronix.de>
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On 2024-01-29, Luis Chamberlain <mcgrof@kernel.org> wrote:
> You should mention the one case which this patch fixes is:
>
>> CONFIG_BASE_SMALL was used that way in init/Kconfig:
>>   config LOG_CPU_MAX_BUF_SHIFT
>>   	default 12 if !BASE_SMALL
>>   	default 0 if BASE_SMALL
>
> You should then mention this has been using 12 for a long time now
> for BASE_SMALL, and so this patch is a functional fix for those
> who used BASE_SMALL and wanted a smaller printk buffer contribtion per
> cpu. The contribution was only per CPU, and since BASE_SMALL systems
> likely don't have many CPUs the impact of this was relatively small,
> 4 KiB per CPU.  This patch fixes that back down to 0 KiB per CPU.

For printk this will mean that BASE_SMALL systems were probably
previously allocating/using the dynamic ringbuffer and now they will
just continue to use the static ringbuffer. Which is fine and saves
memory (as it should).

Reviewed-by: John Ogness <john.ogness@linutronix.de>