From mboxrd@z Thu Jan  1 00:00:00 1970
From: Suzuki.Poulose@arm.com (Suzuki K. Poulose)
Date: Thu, 3 Mar 2016 15:01:00 +0000
Subject: ARM64: CPU Hotplug: can't enable more cpus than maxcpus value
 (kernel 4.5)
In-Reply-To: <56D85151.9050607@arm.com>
References: <20160303141752.GA12255@localhost.localdomain>
 <20160303144215.GC19139@leverpostej> <56D85151.9050607@arm.com>
Message-ID: <56D851AC.7040908@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 03/03/16 14:59, Suzuki K. Poulose wrote:
> On 03/03/16 14:42, Mark Rutland wrote:
>
>>> However for arm64 it is implemented that cpu_present_mask is
>>> explicetely set accordingly to 'maxcpus' value. Is it design intent ?
>>
>> To some extent, yes.
>>
>> Due to the possibility of a heterogeneous system, we must bring all CPUs
>> online at boot time, and cannot defer this.
>>
>> This is necessary to detect the common subset of supported features, and
>> also to detect the full set of CPUs in the system to correctly apply
>> errata workarounds which require kernel text patching.
>
> We don't have this limitation anymore, as we can check if the booting CPU

s/we can/we do/

for the hotplugged CPUs.

Cheers
Suzuki