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From: Dave Martin <Dave.Martin@arm.com>
To: Andrew Murray <andrew.murray@arm.com>
Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 2/6] arm64: HWCAP: add support for AT_HWCAP2
Date: Fri, 29 Mar 2019 15:39:27 +0000	[thread overview]
Message-ID: <20190329153927.GE3567@e103592.cambridge.arm.com> (raw)
In-Reply-To: <1550751657-30252-3-git-send-email-andrew.murray@arm.com>

On Thu, Feb 21, 2019 at 12:20:53PM +0000, Andrew Murray wrote:
> As we will exhaust the first 32 bits of AT_HWCAP let's start
> exposing AT_HWCAP2 to userspace to give us up to 64 caps.
> 
> Whilst it's possible to use the remaining 32 bits of AT_HWCAP, we
> prefer to expand into AT_HWCAP2 in order to provide a consistent
> view to userspace between ILP32 and LP64. However internal to the
> kernel we prefer to continue to use the full space of elf_hwcap.
> 
> To reduce complexity and allow for future expansion, we now
> represent hwcaps in the kernel as ordinals and use a
> KERNEL_HWCAP_ prefix. This allows us to support automatic feature
> based module loading for all our hwcaps.
> 
> We introduce cpu_set_feature to set hwcaps which compliments the
> existing cpu_have_feature helper. These helpers allow us to clean
> up existing direct uses of elf_hwcap and reduce any future effort
> required to move beyond 64 caps.
> 
> For convenience we also introduce cpu_{have,set}_feature_name which
> makes use of the cpu_feature macro to allow providing a hwcap name
> without a {KERNEL_}HWCAP_ prefix.

[...]

Btw, this series will also need to update Documentation/elf_hwcaps.txt.

(You may have been planning to do that anyway, but I just realised.)

Cheers
---Dave


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  parent reply	other threads:[~2019-03-29 15:39 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-21 12:20 [PATCH v2 0/6] Initial support for CVADP Andrew Murray
2019-02-21 12:20 ` [PATCH v2 1/6] arm64: Handle trapped DC CVADP Andrew Murray
2019-02-21 12:39   ` Mark Rutland
2019-02-21 12:20 ` [PATCH v2 2/6] arm64: HWCAP: add support for AT_HWCAP2 Andrew Murray
2019-02-21 18:45   ` Dave P Martin
2019-02-22 10:35     ` Szabolcs Nagy
2019-03-27 15:02       ` Andrew Murray
2019-03-27 15:24         ` Andrew Murray
2019-03-28 11:27           ` Dave Martin
2019-03-29 16:44             ` Szabolcs Nagy
2019-03-29 16:57               ` Phil Blundell
2019-04-01  8:14                 ` Andrew Murray
2019-03-27 14:53     ` Andrew Murray
2019-03-29 15:39   ` Dave Martin [this message]
2019-02-21 12:20 ` [PATCH v2 3/6] arm64: HWCAP: encapsulate elf_hwcap Andrew Murray
2019-02-21 18:45   ` Dave P Martin
2019-03-27 14:03     ` Andrew Murray
2019-03-28 11:32       ` Dave Martin
2019-02-21 12:20 ` [PATCH v2 4/6] arm64: Expose DC CVADP to userspace Andrew Murray
2019-02-21 12:20 ` [PATCH v2 5/6] arm64: add CVADP support to the cache maintenance helper Andrew Murray
2019-02-21 12:20 ` [PATCH v2 6/6] arm64: Advertise ARM64_HAS_DCPODP cpu feature Andrew Murray

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