Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752719AbdDFCV0 (ORCPT ); Wed, 5 Apr 2017 22:21:26 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:61875 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752118AbdDFCVR (ORCPT ); Wed, 5 Apr 2017 22:21:17 -0400 X-IronPort-AV: E=Sophos;i="5.22,518,1449504000"; d="scan'208";a="17409174" Subject: Re: [RFC PATCH 2/6] x86/apic: Construct a framework for setuping APIC mode as soon as possible To: Thomas Gleixner References: <1490799333-18242-1-git-send-email-douly.fnst@cn.fujitsu.com> <1490799333-18242-3-git-send-email-douly.fnst@cn.fujitsu.com> CC: , , , , , , From: Dou Liyang Message-ID: Date: Thu, 6 Apr 2017 10:21:10 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.106] X-yoursite-MailScanner-ID: 36DD54D14A5C.AC454 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: douly.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4389 Lines: 165 Hi Thomas, At 04/05/2017 07:46 PM, Thomas Gleixner wrote: > On Wed, 29 Mar 2017, Dou Liyang wrote: > >> Now, there are two ways to setup local apic and io-apic in X86 arch: >> 1. In an SMP-capable system, it will be done when preparing the >> cpus in native_smp_prepare_boot_cpu(). >> 2. If UP_LATE_INIT is y, it will be done in smp_init() >> >> And, there are many switches in kernel which can determine the way of >> APIC mode setup, as shown below: >> >> 1. kconfig : >> CONFIG_X86_64; CONFIG_X86_LOCAL_APIC; CONFIG_x86_IO_APIC >> 2. kernel option: disable_apic; skip_ioapic_setup >> 3. BIOS : boot_cpu_has(X86_FEATURE_APIC) >> 4. MP table: smp_found_config >> 5. ACPI: acpi_lapic; acpi_ioapic; nr_ioapic >> >> The setup is late which cause the dump-capture kernel hangs with 'notsc' >> option in 1st kernel option. and the use of these switches is messily. >> >> Before make the APIC mode setup earlier, construct a framework first to >> prepare for the work and make the logic clear. > > Calling that a framework is slightly exaggerated. It's a selector function > for the interrupt delivery mode. > Yes, Selector is what I want. To tell the truth, I've been looking for a word that can summarize this patch for a long time. :) >> #ifdef CONFIG_X86_X2APIC >> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c >> index f4fc949..bf4ccd0 100644 >> --- a/arch/x86/kernel/apic/apic.c >> +++ b/arch/x86/kernel/apic/apic.c >> @@ -1153,6 +1153,63 @@ void __init sync_Arb_IDs(void) >> APIC_INT_LEVELTRIG | APIC_DM_INIT); >> } >> >> +enum apic_bsp_mode { >> + APIC_BSP_MODEL_PIC = 0, >> + APIC_BSP_MODEL_VIRTUAL_WIRE, >> + APIC_BSP_MODEL_SYMMETRIC_IO, >> + APIC_BSP_MODEL_COUNT >> +}; >> + >> +static int __init apic_bsp_mode_check(void) >> +{ >> + >> + /* Check kernel option */ >> + if (disable_apic) { >> + pr_info("APIC disabled by kernel option\n"); > > kernel option is ambiguous. "APIC disabled via kernel command line" is telling > clearly where this comes from. > Thanks, will modify in my next version. >> + return APIC_BSP_MODEL_PIC; >> + } >> + /* Check BOIS */ >> +#ifdef CONFIG_X86_64 >> + /* On 64-bit, The APIC is integrated, So, must have APIC feature */ >> + if (!boot_cpu_has(X86_FEATURE_APIC)) { >> + disable_apic = 1; >> + pr_info("Apic disabled by BIOS\n"); > > Please use APIC consistently. Oops, Yes. > >> + return APIC_BSP_MODEL_PIC; >> + } >> +#else >> + if (!boot_cpu_has(X86_FEATURE_APIC) && >> + APIC_INTEGRATED(boot_cpu_apic_version)) { >> + pr_err("BIOS bug, local APIC #%d not detected!...\n", >> + boot_cpu_physical_apicid); > > Please make that > > pr_err(FW_BUG, "Local APIC %d not detected, force emulation", > boot_cpu_physical_apicid); > > and for consistency reasosns this should also set disable_apic to 1. > >> + return APIC_BSP_MODEL_PIC; Yes. I will. >> + } >> +#endif >> + /* >> + * Check MP table, if neither an integrated nor a separate chip >> + * doesn't exist. >> + */ >> + if (!boot_cpu_has(X86_FEATURE_APIC) && !smp_found_config) { >> + pr_info("BOIS don't support APIC, and no SMP configuration.\n"); > > s/BOIS/BIOS/ > > and for consistency reasosns this should also set disable_apic to 1. > OK. > >> + return APIC_BSP_MODEL_PIC; >> + } >> + >> + /* Check MP table, ps: if the virtual wire has been setup */ >> + if (!smp_found_config) { >> + disable_ioapic_support(); >> + >> + /* Check local APIC, if SMP_NO_CONFIG */ >> + if (!acpi_lapic) >> + pr_info("SMP motherboard not detected\n"); >> + >> + return APIC_BSP_MODEL_VIRTUAL_WIRE; >> + } >> + >> + /* Other checks of ACPI options will be done in each setup function */ >> + >> + return APIC_BSP_MODEL_SYMMETRIC_IO; >> +} >> + >> /* >> * Setup the through-local-APIC virtual wire mode. >> */ >> @@ -1202,6 +1259,22 @@ void apic_virture_wire_mode_setup(void) >> apic_write(APIC_LVT1, value); >> } >> >> +/* init the interrupt routing model for the BSP */ >> +void __init init_bsp_APIC(void) >> +{ >> + switch (apic_bsp_mode_check()) { >> + case APIC_BSP_MODEL_PIC: >> + pr_info("Keep in PIC mode(8259)\n"); >> + return; >> + case APIC_BSP_MODEL_VIRTUAL_WIRE: >> + pr_info("switch to virtual wire model.\n"); > > Please consistently start sentences with upper case letters. Yes, I will check all the sentences and comments again carefully. Thanks, Liyang > > Thanks, > > tglx > > >