Messages in this thread | | | Date | Mon, 1 Sep 2014 18:00:58 +0800 | From | "long.wanglong" <> | Subject | Re: [SMP BUG?] the return value of is_smp() is bug? |
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On 2014/9/1 13:49, Wang Long wrote: > > 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 ? > >
hi Arnd
In above two cases, i also set CONFIG_SMP = y. in addtion, the CONFIG_SMP_ON_UP depends on CONFIG_SMP. when set CONFIG_SMP_ON_UP = y, the value of CONFIG_SMP must be y.
> I write the following patch to test the return value of is_smp(). > > ---------------------------------------- > > Signed-off-by: Wang Long <long.wanglong@huawei.com> > --- > 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? > >
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