Hi, On Fri, Feb 19, 2016 at 05:12:41PM -0800, Yang Shi wrote: > I tried to boot 4.5-rc4 kernel on my CN6880 board, but it is failed at > booting up secondary cores. The error is: With v4.5-rc5, EBB6800 is booting fine: [ 0.000000] CPU0 revision is: 000d9108 (Cavium Octeon II) [...] [ 2286.273935] SMP: Booting CPU01 (CoreId 1)... [ 2286.278201] CPU1 revision is: 000d9108 (Cavium Octeon II) [...] [ 2287.214953] SMP: Booting CPU31 (CoreId 31)... [ 2287.224668] CPU31 revision is: 000d9108 (Cavium Octeon II) [ 2287.224865] Brought up 32 CPUs > CPU31 revision is: 000d9101 (Cavium Octeon II) > SMP: Booting CPU32 (CoreId 32)... > Secondary boot timeout > > I passed "numcores=32" in kernel commandline since there are 32 cores ion > CN6880. You shouldn't have CPU32 in that case, the numbering starts from zero. Also the coremask is 32-bit. I can reproduce your issue with CONFIG_NR_CPUS=64. Possibly this code is incorrect for NR_CPUS bigger than 32: /* The present CPUs get the lowest CPU numbers. */ cpus = 1; for (id = 0; id < NR_CPUS; id++) { if ((id != coreid) && (core_mask & (1 << id))) { set_cpu_possible(cpus, true); set_cpu_present(cpus, true); What CONFIG_NR_CPUS did you use? A.