linux-kernel - Re: [PATCH] x86, efi: retry ExitBootServices() on failure

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Message-ID: <20130617101745.GB8569@console-pimps.org>
Date:	Mon, 17 Jun 2013 11:17:45 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	Joey Lee <JLee@...e.com>, Zach Bobroff <zacharyb@....com>,
	Matt Fleming <matt.fleming@...el.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] x86, efi: retry ExitBootServices() on failure

On Mon, 17 Jun, at 10:46:28AM, Jan Beulich wrote:
> To me, all this looks like it is being done on phenomenological basis,
> taking a particular build of a particular firmware implementation as
> the reference. Imo we shouldn't change the code in this way. This
> also applies to the fact that the step is being doubled rather than
> e.g. tripled: With it ending up a "again" anyway (see below), what's
> the point of avoiding one more of the iterations?
> 
> Generic considerations would result in the increment being at least
> 3 * element size; twice the element size assumes that the allocator
> would behave in certain ways (like returning the head or tail part of
> a larger piece of memory).
 
I have no issue with changing the multiplier. But let's get
clarification from Zach as to what exactly is going on here.

> I agree that there ought to be an upper limit. But a single retry here
> again looks like a tailored solution to a particular observed (mis-)
> behavior, rather than something resulting from general considerations.

What value would you suggest for the retry?

-- 
Matt Fleming, Intel Open Source Technology Center
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