Subject: [PATCH] ARM64 / SMP: Switch pr_err() to pr_debug() for disabled GICC entry

From: [email-masked] (Hanjun Guo)
Date: Fri, 3 Jul 2015 09:15:38 +0800

On 2015/7/3 0:29, Catalin Marinas wrote:
> On Wed, Jul 01, 2015 at 09:37:23PM +0800, Hanjun Guo wrote:
>> It is normal that firmware presents GICC entry or entries (processors)
>> with disabled flag in ACPI MADT, taking a system of 16 cpus for example,
>> ACPI firmware may present 8 enabled first with another 8 cpus disabled
>> in MADT, the disabled cpus can be hot-added later.
>>
>> Firmware may also present more cpus than the hardware actually has, but
>> disabled the unused ones, and easily enable it when the hardware has such
>> cpus to make the firmware code scalable.
>>
>> So that's not an error for disabled cpus in MADT, we can switch
>> pr_err() to pr_debug() instead.
>>
>> Signed-off-by: Hanjun Guo <[email-masked]>
>> ---
>>  arch/arm64/kernel/smp.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
>> index 4b2121b..5caf04a 100644
>> --- a/arch/arm64/kernel/smp.c
>> +++ b/arch/arm64/kernel/smp.c
>> @@ -402,7 +402,7 @@ acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
>>  	}
>>  
>>  	if (!(processor->flags & ACPI_MADT_ENABLED)) {
>> -		pr_err("skipping disabled CPU entry with 0x%llx MPIDR\n", hwid);
>> +		pr_debug("skipping disabled CPU entry with 0x%llx MPIDR\n", hwid);
> That's a pretty harmless change. But looking at the use-case, would we
> expect the disabled entries to have a valid hwid? I guess such hwid is
> not known, especially if we can hot-plug some CPU at a later time. If

Good point, usually it's invalid hwid.

> that's the case, can we also move this check before the hwid one?

Yes, fully agree, thanks for catching this, will update the patch.

Thanks
Hanjun