From: Yao Qi <qiyaoltc@gmail.com>
To: Dave Martin <Dave.Martin@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Marc Zyngier <Marc.Zyngier@arm.com>,
Alan Hayward <alan.hayward@arm.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
linux-arch@vger.kernel.org, libc-alpha@sourceware.org,
Florian Weimer <fweimer@redhat.com>,
Joseph Myers <joseph@codesourcery.com>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
Torvald Riegel <triegel@redhat.com>,
gdb@sourceware.org
Subject: Re: [RFC PATCH 07/10] arm64/sve: Add vector length inheritance control
Date: Mon, 16 Jan 2017 12:27:55 +0000 [thread overview]
Message-ID: <20170116122755.GH28060@E107787-LIN> (raw)
In-Reply-To: <1484220369-23970-8-git-send-email-Dave.Martin@arm.com>
On 17-01-12 11:26:06, Dave Martin wrote:
> Currently the vector length is inherited across both fork() and
> exec().
>
> Inheritance across fork() is desirable both for creating a copy of
> a process (traditional fork) or creating a thread (where we want
> all threads to share the same VL by default).
>
> Inheritance across exec() is less desirable, because of the ABI
> impact of large vector lengths on the size of the signal frame --
> when running a new binary, there is no guarantee that the new
> binary is compatible with these ABI changes.
>
> This flag makes the vector length non-inherited by default.
Can we make vector length inherited across fork but non-inherited
across exec by default?
> Instead, the vector length is reset to a system default value,
> unless the THREAD_VL_INHERIT flag has been set for the thread.
>
> THREAD_VL_INHERIT is currently sticky: i.e., if set, it gets
> inherited too. This behaviour may be refined in future if it is
> not flexible enough.
>
--
Yao (齐尧)
next prev parent reply other threads:[~2017-01-16 12:28 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-12 11:25 [RFC PATCH 00/10] arm64/sve: Add userspace vector length control API Dave Martin
2017-01-12 11:25 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 01/10] prctl: Add skeleton for PR_SVE_{SET,GET}_VL controls Dave Martin
2017-01-12 11:26 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 02/10] arm64/sve: Track vector length for each task Dave Martin
2017-01-12 11:26 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 03/10] arm64/sve: Set CPU vector length to match current task Dave Martin
2017-01-12 11:26 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 04/10] arm64/sve: Factor out clearing of tasks' SVE regs Dave Martin
2017-01-12 11:26 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 05/10] arm64/sve: Wire up vector length control prctl() calls Dave Martin
2017-01-12 11:26 ` [RFC PATCH 06/10] arm64/sve: Disallow VL setting for individual threads by default Dave Martin
2017-01-16 11:34 ` Yao Qi
2017-01-16 11:34 ` Yao Qi
2017-01-16 12:23 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 07/10] arm64/sve: Add vector length inheritance control Dave Martin
2017-01-16 12:27 ` Yao Qi [this message]
2017-01-16 13:34 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 08/10] arm64/sve: ptrace: Wire up vector length control and reporting Dave Martin
2017-01-16 12:20 ` Yao Qi
2017-01-16 12:20 ` Yao Qi
2017-01-16 13:32 ` Dave Martin
2017-01-16 15:11 ` Yao Qi
2017-01-16 15:11 ` Yao Qi
2017-01-16 15:47 ` Pedro Alves
2017-01-16 16:31 ` Dave Martin
2017-01-16 16:31 ` Dave Martin
2017-01-17 10:03 ` Dave Martin
2017-01-17 10:03 ` Dave Martin
2017-01-17 13:31 ` Alan Hayward
2017-01-19 17:11 ` Dave Martin
2017-01-19 17:11 ` Dave Martin
2017-01-12 11:26 ` [RFC PATCH 09/10] arm64/sve: Enable default vector length control via procfs Dave Martin
2017-01-12 11:26 ` [RFC PATCH 10/10] Revert "arm64/sve: Limit vector length to 512 bits by default" Dave Martin
2017-01-12 11:26 ` Dave Martin
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