linux-kernel - Re: [RESEND PATCH 0/1] Fix the "hard LOCKUP" when running a heavy loading

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Date:	Tue, 3 Nov 2015 20:00:06 +0800
From:	"Huang, Tao" <huangtao@...k-chips.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Caesar Wang <wxt@...k-chips.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>, sjg@...omium.org,
	Stephen Boyd <sboyd@...eaurora.org>, dianders@...omium.org,
	linux-kernel@...r.kernel.org, Nadav Haklai <nadavh@...vell.com>,
	linux-rockchip@...ts.infradead.org, cwz@...k-chips.com,
	Jonathan Stone <j.stone@...sung.com>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org, hl@...k-chips.com
Subject: Re: [RESEND PATCH 0/1] Fix the "hard LOCKUP" when running a heavy
 loading

Hello Russell:

在 2015年11月03日 19:14, Russell King - ARM Linux 写道:
> On Tue, Nov 03, 2015 at 04:10:08PM +0800, Caesar Wang wrote:
>> As the Russell said:
>> "in other words, which can be handled by updating a control register in
>> the firmware or boot loader"
>> Maybe the better solution is in firmware.
> 
> The full quote is:
> 
> "I think we're at the point where we start insisting that workarounds
> which are simple enable/disable feature bit operations (in other words,
> which can be handled by updating a control register in the firmware or
> boot loader) must be done that way, and we are not going to add such
> workarounds to the kernel anymore."
> 
> The position hasn't changed.  Workarounds such as this should be handled
> in the firmware/boot loader before control is passed to the kernel.
> 
> The reason is very simple: if the C compiler can generate code which
> triggers the bug, it can generate code which triggers the bug in the
> boot loader.  So, the only place such workarounds can be done is before
> any C code gets executed.  Putting such workarounds in the kernel is
> completely inappropriate.

I agree with your reason for CPU0. But how about CPU1~3 if we don't use
any firmware such as ARM Trusted Firmware to take control of CPU power
on? If the CPU1~3 will run on Linux when its first instruction is running?

BTW I don't want to argue with you the workaround is right or wrong
because I know the errata just happen on r0p0 not r0p1.

> 
> Sorry, I'm not going to accept this workaround into the kernel.

It seems we should introduce some code outside the kernel to do such
initialization?

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