linux-kernel - Re: [regression, bisected] x86: efi: Pass boot services variable info to runtime code

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Date:	Fri, 31 May 2013 13:06:09 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Russ Anderson <rja@....com>, joeyli <jlee@...e.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	matt.fleming@...el.com, linux-efi@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [regression, bisected] x86: efi: Pass boot services variable
 info to runtime code

On Fri, 31 May 2013, Ingo Molnar wrote:

> So this change needs to be reverted or fixed.

I don't think anyone is arguing against that.

My remark was purely to describe the current status quo and help to 
understand what exactly is happening, i.e.:

- QueryVariableInfo() should be a valid thing to do from inside boot  
  environment, according to the spec
- now we see that at least SGI bios (an probably other incarnations) 
  think otherwise
- if we are not able to fix / work around the bug in BIOS (*), we have to 
  make a choice between two evils -- either increase likelyhood of 
  bricking certain machines due to filling the EFI storage space, or 
  break booting on broken BIOSen
- the theory is that Borislav's 1:1 mapping patches will work this around; 
  one of the supporting arguments being that it's probably what Windows is 
  doing. I believe Borislav is in the process of testing this. But the 
  patches are not ready for mainline yet.

(*) If one would be naive enough, he'd believe that the pressure should be 
    put on the BIOS writers instead of OS to fix the bug :)

-- 
Jiri Kosina
SUSE Labs
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