linux-kernel - RE: [RFC] ACPI, APEI, Generic Hardware Error Source POLL/IRQ/NMI notification type support

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Date:	Thu, 16 Dec 2010 08:45:06 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	Len Brown <lenb@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: RE: [RFC] ACPI, APEI, Generic Hardware Error Source POLL/IRQ/NMI
 notification type support

On Thu, 2010-12-16 at 00:40 +0800, Luck, Tony wrote:
> >Because the memory area used to transfer hardware error information
> >from BIOS to Linux can be determined only in NMI, IRQ or timer
> >handler, but general ioremap can not be used in atomic context, so a
> >special version of atomic ioremap is implemented for that.
> >
> >Known issue:
> >
> >- Error information can not be printed for recoverable errors notified
> >  via NMI, because printk is not NMI-safe. Will fix this via delay
> >  printing to IRQ context via irq_work or make printk NMI-safe.
> 
> Would it be possible to defer the "ioremap" to a work queue too? Then
> we wouldn't need the special versions of ioremap.

For recoverable error, we can defer the "ioremap" to a work queue,
because most recoverable action can take place only there in fact. But
for fatal error, I think it is too late to be processed in a work queue,
we need go panic as soon as possible to prevent data corruption.

Best Regards,
Huang Ying


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