linux-kernel - Re: srat: harsh hot-pluggable memory check?

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Message-ID: <20130110200223.GH30577@one.firstfloor.org>
Date:	Thu, 10 Jan 2013 21:02:23 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Davidlohr Bueso <davidlohr.bueso@...com>
Cc:	linux-acpi@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
	zeus@....org, linux-kernel@...r.kernel.org
Subject: Re: srat: harsh hot-pluggable memory check?

> This only mentions that the system supports hot-plugging, and IMHO if the
> user decides not to use CONFIG_MEMORY_HOTPLUG, it shouldn't be considered an error.
> Therefore would it be ok to drop the check? Or am I missing something?

The very strict checks were originally implemented because various early
BIOS had largely fictional SRATs, and trusting them blindly caused
boot failures or a lot of wasted memory for unnecessary hotplug zones. 
The wasted memory was mainly a problem with the old memory hotplug
implementation that pre-allocated memmaps, that's not a problem anymore.
However there may be still some other failure cases.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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