From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Thu, 3 Jan 2013 12:21:00 +0000
Subject: [PATCH] ARM: call disable_nonboot_cpus() from machine_shutdown()
In-Reply-To: <20130103120259.GB5193@mudshark.cambridge.arm.com>
References: <1357160861-26282-1-git-send-email-swarren@wwwdotorg.org>
 <50E4C9C6.20609@codeaurora.org>
 <20130103120259.GB5193@mudshark.cambridge.arm.com>
Message-ID: <20130103122100.GN2631@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, Jan 03, 2013 at 12:02:59PM +0000, Will Deacon wrote:
> You need the smp_send_stop call in order to send the cpu_kill (looks like
> tegra needs die and then kill). So you really need hotplug support as well
> as suspend for this to do much (if not, the secondaries end up spinning
> with interrupts disabled which is probably the best we can do anyway).
> 
> We could add SUSPEND as a KEXEC dependency if SMP (we already have HOTPLUG
> there) if you like?

Or we could look into bringing in the code to do this when KEXEC is
enabled - which would mean an amount of restructuring of the Kconfig
files.

In other words, go from this:

config SUSPEND
        bool "Suspend to RAM and standby"
        depends on ARCH_SUSPEND_POSSIBLE
        default y

config HIBERNATE_CALLBACKS
        bool

config PM_SLEEP
        def_bool y
        depends on SUSPEND || HIBERNATE_CALLBACKS

config PM_SLEEP_SMP
        def_bool y
        depends on SMP
        depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
        depends on PM_SLEEP
        select HOTPLUG
        select HOTPLUG_CPU

to:

config SUSPEND
	bool...
	depends on ARCH_SUSPEND_POSSIBLE
	default y
	select PM_SLEEP

config HIBERNATE_CALLBACKS
	bool
	select PM_SLEEP

config PM_SLEEP
	bool
	select PM_SLEEP_SMP if SMP && (ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE)

config PM_SLEEP_SMP
	bool
        select HOTPLUG
        select HOTPLUG_CPU

This means we could have KEXEC select PM_SLEEP_SMP (and maybe PM_SLEEP) as
required, rather than bringing in the entire suspend support just to have
working kexec.

However, how many platforms don't have suspend support enabled?