linux-kernel - Re: [PATCH] arm64: Expose TASK

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Message-ID: <CED1E802-65C5-48B9-8165-46684BE81164@codeaurora.org>
Date:	Wed, 17 Aug 2016 07:12:06 -0400
From:	Christopher Covington <cov@...eaurora.org>
To:	Catalin Marinas <catalin.marinas@....com>
CC:	Will Deacon <will.deacon@....com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Mark Rutland <mark.rutland@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	James Hogan <james.hogan@...tec.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Jon Masters <jcm@...hat.com>,
	Jeremy Linton <jeremy.linton@....com>
Subject: Re: [PATCH] arm64: Expose TASK_SIZE to userspace via auxv



On August 17, 2016 6:30:06 AM EDT, Catalin Marinas <catalin.marinas@....com> wrote:
>On Tue, Aug 16, 2016 at 02:32:29PM -0400, Christopher Covington wrote:
>> Some userspace applications need to know the maximum virtual address
>they can
>> use (TASK_SIZE).
>
>Just curious, what are the cases needing TASK_SIZE in user space?

Checkpoint/Restore In Userspace and the Mozilla Javascript Engine https://bugzilla.mozilla.org/show_bug.cgi?id=1143022 are the specific cases I've run into. I've heard LuaJIT might have a similar situation. In general I think making allocations from the top down is a shortcut for finding a large unused region of memory.

Thanks,
Cov

-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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