Message-ID: <493F2009.6060300@zytor.com>
Date: Tue, 09 Dec 2008 17:48:57 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Yinghai Lu <yinghai@kernel.org>
CC: Zachary Amsden <zach@vmware.com>, Huang Ying <ying.huang@intel.com>,
       Jeremy Fitzhardinge <jeremy@goop.org>,
       Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>, norman@thebacks.co.uk,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Greg KH <gregkh@suse.de>, Alok Kataria <alokkataria1@gmail.com>,
       =?UTF-8?B?QnJ1bm8gUHLDqW1vbnQ=?= <"bruno .premont"@restena.lu>,
       xl@xlsigned.net, dsd@gentoo.org
Subject: Re: [PATCH] Fix VMI crash on boot in 2.6.27+ kernels
References: <1228870222.8766.15.camel@bodhitayantram.eng.vmware.com> <86802c440812091715r775d514eh3acf9add9e24184e@mail.gmail.com>
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Yinghai Lu wrote:
> 
> VMI initialiation can relocate the fixmap, causing early_ioremap
> to malfunction if it is initialized before the relocation.  The
> ioremap area is low enough in virtual address space that no actual
> collision occurs, however, because the pagetables for it were not
> allocated under VMI mode, the pagetable updates are dropped by
> the hypervisor as irrelevant, resulting in a crash on boot.
> 

I have mentioned in the past that I think the very concept of relocating
the fixmap to be utterly braindead.  Instead, I believe we should locate
it low in kernel space so it doesn't have to be relocated.  It's
unfortunately a relatively large change.

	-hpa
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