From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752072AbaIAFvr (ORCPT ); Mon, 1 Sep 2014 01:51:47 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:3504 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078AbaIAFvq (ORCPT ); Mon, 1 Sep 2014 01:51:46 -0400 From: Wang Long To: , , , , , CC: , , Subject: [SMP BUG?] the return value of is_smp() is bug? Date: Mon, 1 Sep 2014 13:49:23 +0800 Message-ID: <1409550563-92081-1-git-send-email-long.wanglong@huawei.com> X-Mailer: git-send-email 1.8.3.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.200] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi,all In kernel 3.17-rc2, when i set CONFIG_HAVE_SMP = y and CONFIG_SMP_ON_UP = y in .config file. the secondary core can not boot. when i set CONFIG_HAVE_SMP = y and CONFIG_SMP_ON_UP = n in .config file, the secondary core can boot. But this does not happen in kernel 3.10 lts kernel, Whether the CONFIG_SMP_ON_UP is set yes or no ,the secondary core can boot. Does the meaning of CONFIG_SMP_ON_UP changed or this is a bug in kernel 3.17-rc2 ? I write the following patch to test the return value of is_smp(). ---------------------------------------- Signed-off-by: Wang Long --- arch/arm/kernel/setup.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index 84db893d..fbeb67f 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -925,6 +925,11 @@ void __init setup_arch(char **cmdline_p) arm_dt_init_cpu_maps(); psci_init(); #ifdef CONFIG_SMP + + if (is_smp() == 1) + printk("is_smp() return true;\n"); + else if (is_smp() == 0) + printk("is_smp() return false;\n"); if (is_smp()) { if (!mdesc->smp_init || !mdesc->smp_init()) { if (psci_smp_available()) kernel version: 3.17-rc2 config: set CONFIG_HAVE_SMP = y and CONFIG_SMP_ON_UP = y command: # qemu-system-arm -M vexpress-a9 -smp 2 -m 128M -kernel arch/arm/boot/zImage -nographic The output: .......... is_smp() return false; CPU: Testing write buffer coherency: ok missing device node for CPU 0 CPU0: thread -1, cpu 0, socket 0, mpidr 80000000 Setting up static identity map for 0x604643d8 - 0x60464430 Brought up 1 CPUs SMP: Total of 1 processors activated. CPU: All CPU(s) started in SVC mode. ........... config: set CONFIG_HAVE_SMP = y and not set CONFIG_SMP_ON_UP command: # qemu-system-arm -M vexpress-a9 -smp 2 -m 128M -kernel arch/arm/boot/zImage -nographic The output: ..... Memory policy: Data cache writealloc is_smp() return true; sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 178956969942ns ...... ...... CPU: Testing write buffer coherency: ok missing device node for CPU 0 missing device node for CPU 1 CPU0: thread -1, cpu 0, socket 0, mpidr 80000000 Setting up static identity map for 0x60463ef8 - 0x60463f50 CPU1: Booted secondary processor CPU1: thread -1, cpu 1, socket 0, mpidr 80000001 Brought up 2 CPUs SMP: Total of 2 processors activated. CPU: All CPU(s) started in SVC mode. devtmpfs: initialized ....... Any ideas? -- 1.7.9.5