Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751681Ab3HTQXI (ORCPT ); Tue, 20 Aug 2013 12:23:08 -0400 Received: from service87.mimecast.com ([91.220.42.44]:35852 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751625Ab3HTQXG convert rfc822-to-8bit (ORCPT ); Tue, 20 Aug 2013 12:23:06 -0400 Message-ID: <521397FD.8040102@arm.com> Date: Tue, 20 Aug 2013 17:23:25 +0100 From: Sudeep KarkadaNagesha User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Will Deacon CC: Sudeep KarkadaNagesha , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Lorenzo Pieralisi , Catalin Marinas , Thomas Gleixner , Daniel Lezcano Subject: Re: [PATCH v3 4/6] ARM64: arch_timer: configure and enable event stream References: <1374492082-13686-1-git-send-email-Sudeep.KarkadaNagesha@arm.com> <1376414984-14182-1-git-send-email-Sudeep.KarkadaNagesha@arm.com> <1376414984-14182-5-git-send-email-Sudeep.KarkadaNagesha@arm.com> <20130820132712.GE26129@mudshark.cambridge.arm.com> <52137CD5.7010201@arm.com> <20130820161658.GD27819@mudshark.cambridge.arm.com> In-Reply-To: <20130820161658.GD27819@mudshark.cambridge.arm.com> X-OriginalArrivalTime: 20 Aug 2013 16:23:01.0547 (UTC) FILETIME=[8A5617B0:01CE9DC1] X-MC-Unique: 113082017230401801 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2523 Lines: 61 On 20/08/13 17:16, Will Deacon wrote: > On Tue, Aug 20, 2013 at 03:27:33PM +0100, Sudeep KarkadaNagesha wrote: >> On 20/08/13 14:27, Will Deacon wrote: >>> On Tue, Aug 13, 2013 at 06:29:42PM +0100, Sudeep KarkadaNagesha wrote: >>>> diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h >>>> index 6d4482f..effd8f9 100644 >>>> --- a/arch/arm64/include/asm/hwcap.h >>>> +++ b/arch/arm64/include/asm/hwcap.h >>>> @@ -30,6 +30,7 @@ >>>> #define COMPAT_HWCAP_IDIVA (1 << 17) >>>> #define COMPAT_HWCAP_IDIVT (1 << 18) >>>> #define COMPAT_HWCAP_IDIV (COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT) >>>> +#define COMPAT_HWCAP_EVTSTRM (1 << 21) >>> >>> Looking at the context, we should also add COMPAT_HWCAP_LPAE as a separate >>> patch (not part of this series). >>> >> Ok make sense, I can do that. IIUC even this needs at least under some >> config option, assuming can't be dynamic ? > > I'm not sure I follow you... if you're asking whether the LPAE HWCAP should > be dynamic for ARMv8, then no, since the capabilities offered by LPAE are > included in ARMv8 as far as userspace is concerned. > Ok, then it can be in the default list of compat hwcap. >>>> #ifndef __ASSEMBLY__ >>>> /* >>>> @@ -41,7 +42,8 @@ >>>> COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\ >>>> COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\ >>>> COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\ >>>> - COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV) >>>> + COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV|\ >>>> + COMPAT_HWCAP_EVTSTRM) >>> >>> So here you're hardcoding COMPAT_HWCAP_EVTSTRM in the COMPAT_ELF_HWCAP, yet >>> we only enable the native one from the arch-timer driver. The question then is >>> "Can we rely on the event-stream working for AArch64?". If so, we don't need >>> the native hwcap at all. If not, then we need to make the compat hwcap >>> dynamic. >> >> How about something like this ? I am not sure if >> arch/arm64/kernel/setup.c is apt place for compat_elf_hwcap though. > > Looks like the right sort of idea, yes. I can't think of a better place to > put it. You could adjust it slightly so that COMPAT_ELF_HWCAP stays like it > is, with an extra '| compat_dyn_elf_hwcap' on the end, but I have no real > preference. > Yes that's better, will do this way. Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/