linux-kernel - Re: 2.6.39.1 immediately reboots/resets on EFI system

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Date:	Tue, 14 Jun 2011 15:55:32 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Maarten Lankhorst <m.b.lankhorst@...il.com>
Cc:	Yinghai Lu <yinghai@...nel.org>, Jim Bos <jim876@...all.nl>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Greg KH <gregkh@...e.de>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: Re: 2.6.39.1 immediately reboots/resets on EFI system

On Tue, Jun 14, 2011 at 04:50:33PM +0200, Maarten Lankhorst wrote:
> Didn't notice it before, but my efi memmap has:
> [    0.000000] EFI: mem00: type=3, attr=0xf, range=[0x0000000000000000-0x0000000000008000) (0MB)
> 
> Later on this range gets reserved for bios:
> 
> [    0.000000] e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved)
> [    0.000000] e820 remove range: 00000000000a0000 - 0000000000100000 (usable)
> 
> So I've added a check for e820.

I've got a patch that ignores any EFI mapping at page 0, since it's 
pretty much guaranteed to provide bogosity. Checking e820 might well be 
a cleaner approach, though.

> Also with some digging into the swapper warning, it appears to be because
> some memory was allocated in the _init part of the kernel, which you didn't check for.
> this probably caused the warnings I had. Now I made sure to cover
> the entire kernel from _text to _end, which should cover the entire kernel.

Ah, ok, that makes sense. If you post that I'll take a look.

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