linux-kernel - Re: [PATCH] arm64/sve: Document that __SVE_VQ

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Message-ID: <ZcOdZNEDXy14OGGI@finisterre.sirena.org.uk>
Date: Wed, 7 Feb 2024 15:10:28 +0000
From: Mark Brown <broonie@...nel.org>
To: Dave Martin <Dave.Martin@....com>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64/sve: Document that __SVE_VQ_MAX is much larger
 than needed

On Wed, Feb 07, 2024 at 01:39:13PM +0000, Dave Martin wrote:

> How about something along the lines of:

> /*
>  * Yes, this is 512 QUADWORDS.
>  * To help ensure forward portability, this is much larger than the
>  * current maximum value defined by the SVE architecture.
>  * While arrays or static allocations can be sized based on this value,
>  * watch out!  It will waste a surprisingly large amount of memory.
>  * Dynamic sizing based on the actual runtime vector length is likely to
>  * be preferable for most purposes.
>  */

That works for me.  The cost of initialising can also add up in
emulation.

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