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From: steve.capper@arm.com (Steve Capper)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 0/5] 52-bit userspace VAs
Date: Fri, 7 Sep 2018 14:59:08 +0100	[thread overview]
Message-ID: <20180907135907.snnns2aym3jhu2cc@capper-debian.cambridge.arm.com> (raw)
In-Reply-To: <53f6d3aa-ffd9-8452-4ad6-847132b975a9@redhat.com>

On Fri, Sep 07, 2018 at 02:22:49AM -0400, Jon Masters wrote:
> On 08/29/2018 08:45 AM, Steve Capper wrote:
> > This patch series brings support for 52-bit userspace VAs to systems that
> > have ARMv8.2-LVA and are running with a 48-bit VA_BITS and a 64KB
> > PAGE_SIZE.
> > 
> > If no hardware support is present, the kernel runs with a 48-bit VA space
> > for userspace.
> > 
> > Userspace can exploit this feature by providing an address hint to mmap
> > where addr[51:48] != 0. Otherwise all the VA mappings will behave in the
> > same way as a 48-bit VA system (this is to maintain compatibility with
> > software that assumes the maximum VA size on arm64 is 48-bit).
> > 
> > This patch series applies to 4.19-rc1.
> > 
> > Testing was in a model with Trusted Firmware and UEFI for boot.
> 
> This is great stuff. I'm hoping to catch up at Connect and discuss.
> 
> Help me understand something. Without the kernel side of this patch, and
> the increase in linear map for installed RAM, what upside do I see other
> than being able to allocate from a higher VA space?
>

Hi Jon,
The main benefit from this series is that it allows for 52-bit VA
testing to take place in userspace on smaller systems.

Cheers,
-- 
Steve

      reply	other threads:[~2018-09-07 13:59 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-29 12:45 [PATCH 0/5] 52-bit userspace VAs Steve Capper
2018-08-29 12:45 ` [PATCH 1/5] arm64: mm: Introduce DEFAULT_MAP_WINDOW Steve Capper
2018-08-29 12:45 ` [PATCH 2/5] arm64: mm: introduce 52-bit userspace support Steve Capper
2018-09-21 17:40   ` Catalin Marinas
2018-09-27 13:50     ` Steve Capper
2018-09-27 14:48       ` Steve Capper
2018-10-01 10:28         ` Catalin Marinas
2018-10-01 10:50           ` Steve Capper
2018-08-29 12:45 ` [PATCH 3/5] arm64: mm: Copy over arch_get_unmapped_area Steve Capper
2018-09-07  6:15   ` Jon Masters
2018-09-07 14:04     ` Steve Capper
2018-10-17 14:52       ` Steve Capper
2018-08-29 12:45 ` [PATCH 4/5] arm64: mmap: Allow for "high" 52-bit VA allocations Steve Capper
2018-09-21 17:11   ` Catalin Marinas
2018-08-29 12:45 ` [PATCH 5/5] arm64: mm: Activate 52-bit userspace VA support Steve Capper
2018-09-07  6:22 ` [PATCH 0/5] 52-bit userspace VAs Jon Masters
2018-09-07 13:59   ` Steve Capper [this message]

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