From mboxrd@z Thu Jan  1 00:00:00 1970
From: vladimir.murzin@arm.com (Vladimir Murzin)
Date: Wed, 20 Dec 2017 09:55:00 +0000
Subject: [PATCH] ARM: NOMMU: Setup VBAR/Hivecs for secondaries cores
In-Reply-To: <20171220045219.GA6416@afzalpc>
References: <1513679029-5915-1-git-send-email-vladimir.murzin@arm.com>
 <20171219112954.GA14910@afzalpc>
 <4e80e47a-d7b4-c09c-fe88-a7dff6522038@arm.com>
 <20171220045219.GA6416@afzalpc>
Message-ID: <b0e23a0b-8488-b1bc-8afe-cd68e47b9ad6@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi,

On 20/12/17 04:52, afzal mohammed wrote:
> Hi,
> 
> On Tue, Dec 19, 2017 at 02:44:01PM +0000, Vladimir Murzin wrote:
> 
>>> Was the issue observed on Cortex-R ?, and was it occuring with
>>> CONFIG_CPU_HIGH_VECTOR enabled or disabled ?
>>
>> I caught it when was trying to setup VBAR and after code inspection I
>> noticed that setting of Hivecs were changed as well.
> 
> Thinking again about this, should the Hivecs setting on secondary
> CPU's be done (till a requirement comes) ?
> 
> ARM ARM deprecates using Hivecs setting on ARMv7-R, so this issue
> might not be hit in practice for R class. While pre-ARMv7, lack of
> Hivecs setting for secondaries, it seems can affect only ARMv6k
> (multi-processing support added here ?) and i am making a guess that
> even if there are ARMv6k with more than one core available, they might
> not yet have run with MMU disabled to hit this case, probably the
> reason no one has reported issue for long.

I've just reported an issue, no? :)

> 
> Perhaps, we can avoid configuring Hivecs for secondaries until some
> one needs it ?

Well, before ad475117d201, Hivec would be enabled for secondaries via

secondary_startup
	-> __after_proc_init

after that commit it is not true, so it is kind of regression.

Additionally, patch is not about Hivec only, but VBAR as well and TBH I
don't follow what is your proposal...

Cheers
Vladimir

> 
> afzal
>