linux-kernel - Re: [BUG]: DELL XPS 8500 become a brick after fill too many entries to nvram.

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Date:	Wed, 13 Nov 2013 14:08:14 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Madper Xie <cxie@...hat.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [BUG]: DELL XPS 8500 become a brick after fill too many entries
 to nvram.

On Wed, 13 Nov, at 08:57:49PM, Madper Xie wrote:
> 
> matt@...sole-pimps.org writes:
> 
> > On Mon, 11 Nov, at 08:38:31PM, Madper Xie wrote:
> >> 
> >> matt@...sole-pimps.org writes:
> >> 
> >> > On Mon, 11 Nov, at 02:15:22PM, Madper Xie wrote:
> >> >> Howdy all,
> >> >>   For now we ensure at least ~5kb free space. But my dell xps still
> >> >>   become a brick after I add too many entries to my nvram. So maybe 5kb
> >> >>   is not safe enough. and 5kb is just aginst Samsung's laptop.
> >> >>   So should we enlarge EFI_MIN_RESERVE?
> >> >
> >
> > OK, that's pretty conclusive. Thanks.
> >
> Ouch, Sorry. My mistake. Seems filling too much entries to nvram is not
> the murderer...
> For testing, I using following command to fill my nvram:
> head -c20480 /dev/urandom | efibootmgr --quiet --create --append-binary-args - 
> 
> For occupy lots of nvram space, I run it many times. But when I try to
> find the threshold, I find the real murderer is that command. I mean my
> dell xps will bricked even if I just run the command once and have more
> than 100kb free space...
> 
> So the murderer is the new added boot entry. I don't really know if it's
> still a bug. And I apologize for my mistake. :-(

OK, it looks like the firmware Boot Manager gets very confused when it
tries to parse the Boot Load Option you created with efibootmgr. This
looks like a general firmware bug and not something we need to worry
about in the kernel.

-- 
Matt Fleming, Intel Open Source Technology Center
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