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Re: [PATCH v3 14/28] arm64/sve: Backend logic for setting the vector length
- From: Catalin Marinas <catalin dot marinas at arm dot com>
- To: Dave Martin <Dave dot Martin at arm dot com>
- Cc: linux-arm-kernel at lists dot infradead dot org, linux-arch at vger dot kernel dot org, Okamoto Takayuki <tokamoto at jp dot fujitsu dot com>, libc-alpha at sourceware dot org, Ard Biesheuvel <ard dot biesheuvel at linaro dot org>, Szabolcs Nagy <szabolcs dot nagy at arm dot com>, Will Deacon <will dot deacon at arm dot com>, Richard Sandiford <richard dot sandiford at arm dot com>, Alex Bennée <alex dot bennee at linaro dot org>, kvmarm at lists dot cs dot columbia dot edu
- Date: Wed, 11 Oct 2017 17:43:50 +0100
- Subject: Re: [PATCH v3 14/28] arm64/sve: Backend logic for setting the vector length
- Authentication-results: sourceware.org; auth=none
- References: <1507660725-7986-1-git-send-email-Dave.Martin@arm.com> <1507660725-7986-15-git-send-email-Dave.Martin@arm.com>
On Tue, Oct 10, 2017 at 07:38:31PM +0100, Dave P Martin wrote:
> This patch implements the core logic for changing a task's vector
> length on request from userspace. This will be used by the ptrace
> and prctl frontends that are implemented in later patches.
>
> The SVE architecture permits, but does not require, implementations
> to support vector lengths that are not a power of two. To handle
> this, logic is added to check a requested vector length against a
> possibly sparse bitmap of available vector lengths at runtime, so
> that the best supported value can be chosen.
>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> Cc: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>