Hi Geoff, On 23/06/16 18:54, Geoff Levand wrote: > Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the > arm64 architecture that add support for the kexec re-boot mechanism > (CONFIG_KEXEC) on arm64 platforms. > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c > new file mode 100644 > index 0000000..e2904c4 > --- /dev/null > +++ b/arch/arm64/kernel/machine_kexec.c > +/** > + * machine_kexec_prepare - Prepare for a kexec reboot. > + * > + * Called from the core kexec code when a kernel image is loaded. > + * Forbid loading a kexec kernel if we have no way of hotplugging cpus or cpus > + * are stuck in the kernel. This avoids a panic once we hit machine_kexec(). > + */ > +int machine_kexec_prepare(struct kimage *kimage) > +{ > + kimage_start = kimage->start; > + > + if (kimage->type != KEXEC_TYPE_CRASH) { > + if (cpus_are_stuck_in_kernel()) { > + pr_err("Can't kexec: failed CPUs are stuck in the kernel.\n"); We may want to change the word 'failed' here, the helper function now also covers systems that boot secondary processors with spin tables that are stuck in the secondary_holding_pen: > "Can't kexec: secondary CPUs are stuck in the kernel.\n" > + return -EBUSY; > + } > + > + if (num_online_cpus() > 1) { > + if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { > + /* any_cpu as we don't mind being preempted */ > + int any_cpu = raw_smp_processor_id(); > + > + if (cpu_ops[any_cpu]->cpu_die) > + return 0; > + } > + > + pr_err("Can't kexec: no mechanism to offline secondary CPUs.\n"); > + return -EBUSY; > + } This if() {} hunk isn't necessary with the version of cpus_are_stuck_in_kernel() you have in patch 2. This logic is the '|| smp_spin_tables' part of that helper function. (hibernate needed it too) > + } > + > + return 0; > +} > + [ ... ] > +/** > + * machine_kexec - Do the kexec reboot. > + * > + * Called from the core kexec code for a sys_reboot with LINUX_REBOOT_CMD_KEXEC. > + */ > +void machine_kexec(struct kimage *kimage) > +{ > + phys_addr_t reboot_code_buffer_phys; > + void *reboot_code_buffer; > + > + /* > + * New cpus may have become stuck_in_kernel after we loaded the image. > + */ > + BUG_ON(cpus_are_stuck_in_kernel() && (num_online_cpus() > 1)); BUG_ON(cpus_are_stuck_in_kernel() || (num_online_cpus() > 1)); Thanks, James