From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1947689AbdEZKWT (ORCPT ); Fri, 26 May 2017 06:22:19 -0400 Received: from prv3-mh.provo.novell.com ([137.65.250.26]:60703 "EHLO prv3-mh.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1947673AbdEZKWP (ORCPT ); Fri, 26 May 2017 06:22:15 -0400 Subject: Re: [PATCH] ACPI: processor: fix LPI when built as module To: Sudeep Holla , linux-acpi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rafael.j.wysocki@intel.com, catalin.marinas@arm.com, lorenzo.pieralisi@arm.com References: <20170519092837.30991-1-yousaf.kaukab@suse.com> <314aff9d-6c24-e533-ef08-c16bc0816474@arm.com> From: Mian Yousaf Kaukab Message-ID: <0d6edbd9-938c-a926-1480-c11de01ee38d@suse.com> Date: Fri, 26 May 2017 12:21:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:54.0) Gecko/20100101 Thunderbird/54.0 MIME-Version: 1.0 In-Reply-To: <314aff9d-6c24-e533-ef08-c16bc0816474@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/23/17 3:08 PM, Sudeep Holla wrote: > > > On 19/05/17 10:28, Mian Yousaf Kaukab wrote: >> Low Power Idle(LPI) support added acpi_processor_ffh_lpi_probe() and >> acpi_processor_ffh_lpi_enter() as __weak functions and arch code is >> supposed to provide the actual callbacks. This breaks if >> ACPI_PROCESSOR is configured as a module. >> >> Add CONFIG_ARCH_HAS_ACPI_LPI configuration option to fix this. >> > > Rafael didn't like the extra Kconfig option when I first posted > LPI patches. > >> Signed-off-by: Mian Yousaf Kaukab >> --- >> arch/arm64/Kconfig | 1 + >> arch/arm64/kernel/cpuidle.c | 2 ++ >> drivers/acpi/Kconfig | 3 +++ >> drivers/acpi/processor_idle.c | 9 +++++++-- >> 4 files changed, 13 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 848a34116c67..de2f2779cdf5 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -10,6 +10,7 @@ config ARM64 >> select ARCH_HAS_DEBUG_VIRTUAL >> select ARCH_HAS_DEVMEM_IS_ALLOWED >> select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI >> + select ARCH_HAS_ACPI_LPI if ACPI >> select ARCH_HAS_ELF_RANDOMIZE >> select ARCH_HAS_GCOV_PROFILE_ALL >> select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA >> diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c >> index fd691087dc9a..002d9cb890bd 100644 >> --- a/arch/arm64/kernel/cpuidle.c >> +++ b/arch/arm64/kernel/cpuidle.c >> @@ -51,9 +51,11 @@ int acpi_processor_ffh_lpi_probe(unsigned int cpu) >> { >> return arm_cpuidle_init(cpu); >> } >> +EXPORT_SYMBOL(acpi_processor_ffh_lpi_probe); >> >> int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi) >> { >> return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, lpi->index); >> } >> +EXPORT_SYMBOL(acpi_processor_ffh_lpi_enter); > > Won't these 2 export suffice ? [...] No, they don't suffice. > [...] I am just curious why that won't work. I am not really sure. System.map shows the exported symbols as following: ffff000008095898 T acpi_processor_ffh_lpi_probe ffff0000080958f8 T acpi_processor_ffh_lpi_enter ffff000008c19160 R __ksymtab_acpi_processor_ffh_lpi_enter ffff000008c19170 R __ksymtab_acpi_processor_ffh_lpi_probe ffff000008c357f0 r __kcrctab_acpi_processor_ffh_lpi_enter ffff000008c357f8 r __kcrctab_acpi_processor_ffh_lpi_probe ffff000008c4361b r __kstrtab_acpi_processor_ffh_lpi_enter ffff000008c43638 r __kstrtab_acpi_processor_ffh_lpi_probe and 'nm processor.ko' shows that they are defined as weak: 0000000000000d68 W acpi_processor_ffh_lpi_enter 0000000000000cc8 W acpi_processor_ffh_lpi_probe But still weak symbols are happily used when the module is inserted. > Will weak function definitions be still picked when built as modules ? Yes. BR, Yousaf