linux-kernel - Re: [PATCH 1/4] ACPI, APEI, GHES, Prevent GHES to be built as module

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Date:	Tue, 21 Jun 2011 15:30:08 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Len Brown <lenb@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Luck, Tony" <tony.luck@...el.com>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"mjg59@...f.ucam.org" <mjg59@...f.ucam.org>
Subject: Re: [PATCH 1/4] ACPI, APEI, GHES, Prevent GHES to be built as module

Hi, Andi,

Thanks for comments!

On 06/21/2011 03:23 PM, Andi Kleen wrote:
> On Tue, Jun 21, 2011 at 03:16:24PM +0800, Huang Ying wrote:
>> GHES (Generic Hardware Error Source) is used to process hardware error
>> notification in firmware first mode.  But because firmware first mode
>> can be turned on but can not be turned off, it is unreasonable to
>> unload the GHES module with firmware first mode turned on.  To avoid
>> confusion, this patch makes GHES can be enable/disable in
>> configuration time, but not built as module and unload at run time.
> 
> It's better to keep it as a module, but disable unloading.
> You can do that with a __module_get(THIS_MODULE) in the init code
> when FFM is detected.

There are two ways to turn on firmware first mode

1) APEI bit in generic _OSC call
2) Special APEI _OSC call

1) is run before GHES module loading.  If keeping GHES as a module, it
is possible that firmware first mode has been turned on with APEI bit in
generic _OSC call, but GHES module is prevented to be loaded via some
kind of module blacklist.  So I think it is better to prevent GHES to be
built as module.

Best Regards,
Huang Ying
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