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Re: [PATCH v4 20/28] arm64/sve: Add prctl controls for userspace vector length management
- From: Dave Martin <Dave dot Martin at arm dot com>
- To: Alex Bennée <alex dot bennee at linaro dot org>
- Cc: 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>, Catalin Marinas <catalin dot marinas at arm dot com>, Will Deacon <will dot deacon at arm dot com>, kvmarm at lists dot cs dot columbia dot edu, linux-arm-kernel at lists dot infradead dot org
- Date: Sat, 28 Oct 2017 17:05:09 +0100
- Subject: Re: [PATCH v4 20/28] arm64/sve: Add prctl controls for userspace vector length management
- Authentication-results: sourceware.org; auth=none
- References: <1509101470-7881-1-git-send-email-Dave.Martin@arm.com> <1509101470-7881-21-git-send-email-Dave.Martin@arm.com> <87r2toiikt.fsf@linaro.org>
On Fri, Oct 27, 2017 at 06:52:50PM +0100, Alex Bennée wrote:
>
> Dave Martin <Dave.Martin@arm.com> writes:
>
> > This patch adds two arm64-specific prctls, to permit userspace to
> > control its vector length:
> >
> > * PR_SVE_SET_VL: set the thread's SVE vector length and vector
> > length inheritance mode.
> >
> > * PR_SVE_GET_VL: get the same information.
> >
> > Although these prctls resemble instruction set features in the SVE
> > architecture, they provide additional control: the vector length
> > inheritance mode is Linux-specific and nothing to do with the
> > architecture, and the architecture does not permit EL0 to set its
> > own vector length directly. Both can be used in portable tools
> > without requiring the use of SVE instructions.
> >
> > Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Alex Bennée <alex.bennee@linaro.org>
>
> FYI there is a minor conflict applying this on current master.
There are some trivial conflicts with one or two patches that already
went into arm64/for-next/core, so I based on that for this posting, not
torvalds/master.
There's a note in the cover letter giving the precise commit I based
on, though the branch doesn't seem to have moved yet since I posted.
Otherwise, I don't see any conflict -- can you give details?
Cheers
---Dave