Re: [PATCHv3] ARM: omap2+: Revert omap-smp.c changes resetting CPU1 during boot

[Russell King - ARM Linux <linux@armlinux.org.uk>]

On Tue, Mar 28, 2017 at 10:09:44AM -0700, Tony Lindgren wrote:
> OK so how about the following to disable kexec for Andrew's
> test case?

That won't work - the hook you're using is to decide whether a particular
CPU (normally the boot CPU) can be hot-plugged.  It isn't expected to
return false for all.

The code in question is:

        /*
         * Validate that if the current HW supports SMP, then the SW supports
         * and implements CPU hotplug for the current HW. If not, we won't be
         * able to kexec reliably, so fail the prepare operation.
         */
        if (num_possible_cpus() > 1 && platform_can_secondary_boot() &&
            !platform_can_cpu_hotplug())
                return -EINVAL;

and:

int platform_can_cpu_hotplug(void)
{
#ifdef CONFIG_HOTPLUG_CPU
        if (smp_ops.cpu_kill)
                return 1;
#endif

        return 0;
}

Platforms don't get a say in that, other than whether they implement
the operations necessary for hotplug.

-- 
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