Re: 4.5-rc4 kernel is failed to bootup on CN6880

[Aaro Koskinen]

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.