linux-kernel - Re: [PATCH v2 3/3] swiotlb: Add swiotlb=noforce debug option

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Message-ID: <20170104180002.GE31066@e104818-lin.cambridge.arm.com>
Date:   Wed, 4 Jan 2017 18:00:02 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Jonathan Corbet <corbet@....net>,
        Will Deacon <will.deacon@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        David Vrabel <david.vrabel@...rix.com>,
        Juergen Gross <jgross@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v2 3/3] swiotlb: Add swiotlb=noforce debug option

On Fri, Dec 16, 2016 at 02:28:42PM +0100, Geert Uytterhoeven wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 21e2d88637050b7a..24fb691b2da5f78d 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3811,10 +3811,11 @@
>  			it if 0 is given (See Documentation/cgroup-v1/memory.txt)
>  
>  	swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
> -			Format: { <int> | force }
> +			Format: { <int> | force | noforce }
>  			<int> -- Number of I/O TLB slabs
>  			force -- force using of bounce buffers even if they
>  			         wouldn't be automatically used by the kernel
> +			noforce -- Never use bounce buffers (for debugging)

Nitpick (bikeshedding, feel free to ignore): "noforce" looks to me like
the current default behaviour if swiotlb= argument is passed. I would
have preferred "never" or "disable" instead, it has a clearer intent.

-- 
Catalin