From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752199AbaATRjM (ORCPT ); Mon, 20 Jan 2014 12:39:12 -0500 Received: from fw-tnat.austin.arm.com ([217.140.110.23]:17022 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750758AbaATRjK (ORCPT ); Mon, 20 Jan 2014 12:39:10 -0500 Date: Mon, 20 Jan 2014 17:38:38 +0000 From: Catalin Marinas To: Ard Biesheuvel Cc: "linux@arm.linux.org.uk" , "viro@zeniv.linux.org.uk" , "nico@linaro.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v2 0/5] arm64: advertise availability of CRC and crypto instructions Message-ID: <20140120173838.GD29971@arm.com> References: <1387807592-26375-1-git-send-email-ard.biesheuvel@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1387807592-26375-1-git-send-email-ard.biesheuvel@linaro.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 23, 2013 at 02:06:27PM +0000, Ard Biesheuvel wrote: > This series is a followup to the patch that was recently merged by Catalin that > allocates hwcaps bits for CRC and Crypto Extensions instructions so userland can > discover whether the current CPU has any of those capabilities. > > Patch #1 enables ARM support for the ELF_HWCAP2/AT_HWCAP2 ELF auxv entry that > was recently added to the kernel and glibc (2.18). It extends the feature bit > space to 64 bits (on 32-bit architectures) > > Patch #2 adds generic support for ELF_HWCAP2/AT_HWCAP2 to the 32-bit ELF compat > mode for 64-bit architectures. > > Patch #3 adds support for ELF_HWCAP2/AT_HWCAP2 to arm64's 32-bit ELF compat mode > > Patch #4 allocates the HWCAP2 bits in the arch/arm tree. This is necessary > because 32-bit ARM binaries can execute both under ARM and under arm64 kernels, > so there should be agreement about the meaning of feature bits, even if the ARM > kernel has no support yet for ARMv8 32-bit only hardware (such as ARMv8-R). It looks a bit strange to start filling HWCAP2 before HWCAP is full but I guess we want to preserve some future extensions in HWCAP for older glibc. -- Catalin