linux-kernel - Re: [RFC PATCH v2 0/3] genirq, serial: 8250: Workaround to avoid irq=0 for console

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Message-ID: <alpine.DEB.2.11.1507291351530.3825@nanos>
Date:	Wed, 29 Jul 2015 13:53:52 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Peter Hurley <peter@...leysoftware.com>
cc:	Taichi Kageyama <t-kageyama@...jp.nec.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"jiang.liu@...ux.intel.com" <jiang.liu@...ux.intel.com>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jslaby@...e.cz" <jslaby@...e.cz>,
	"prarit@...hat.com" <prarit@...hat.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Subject: Re: [RFC PATCH v2 0/3] genirq, serial: 8250: Workaround to avoid
 irq=0 for console

On Wed, 29 Jul 2015, Peter Hurley wrote:
> On 07/29/2015 06:32 AM, Thomas Gleixner wrote:
> > On Wed, 29 Jul 2015, Taichi Kageyama wrote:
> >> - Keep interrupt disabled on the CPU which is used to detect 
> >>   an interrupt during the timeout of autoconfig_irq().
> >>      + Kick printk() on the CPU which detects interrupt 
> >>        from a console serial port.
> > 
> > This is wrong to begin with. How is that supposed to work on an UP
> > machine? Not at all.
> > 
> > So no, fix the code which has interrupts disabled accross autoprobing
> > and do not try to apply bandaids somewhere else.
> 
> Like printk() from some unrelated driver?

If that's the cause for the wreckage then yes, we need a way to tell
the printk code not to call into the driver until that initialization
step is done. It's that simple.

Thanks,

	tglx
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