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

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Message-ID: <20110621131842.GA4902@srcf.ucam.org>
Date:	Tue, 21 Jun 2011 14:18:42 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Huang Ying <ying.huang@...el.com>, Len Brown <lenb@...nel.org>,
	linux-kernel@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH 1/4] ACPI, APEI, GHES, Prevent GHES to be built as
 module

On Tue, Jun 21, 2011 at 09:23:01AM +0200, 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.

Anything that's enabled by an _OSC call is expected to be available 
immediately. So the choices are either to ensure that GHES support is 
built in, or to make a second _OSC call when the GHES code is loaded. 
We've seen in the PCIe case that many firmware implementations 
misinterpret multiple attempts to set _OSC with the same UUID, and a 
cursory examination of some implementations of the systemwide one 
suggest that we'd see the same issue there.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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