linux-kernel - Re: [PATCH] Modify UEFI anti-bricking code

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Message-ID: <1370448519.6315.36.camel@x230.lan>
Date:	Wed, 5 Jun 2013 16:08:39 +0000
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	Matt Fleming <matt@...sole-pimps.org>
CC:	"Fleming, Matt" <matt.fleming@...el.com>, joeyli <jlee@...e.com>,
	"rja@....com" <rja@....com>, "mingo@...nel.org" <mingo@...nel.org>,
	"torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
	"bp@...en8.de" <bp@...en8.de>, "jkosina@...e.cz" <jkosina@...e.cz>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...ux.intel.com" <hpa@...ux.intel.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"oneukum@...e.de" <oneukum@...e.de>
Subject: Re: [PATCH] Modify UEFI anti-bricking code

On Wed, 2013-06-05 at 16:59 +0100, Matt Fleming wrote:

> +	/* clean DUMMY object */
> +	efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID, 0, 0, NULL);

Hm. Actually, is that going to work? From the spec:

If a preexisting variable is rewritten with different attributes,
SetVariable()shall not modify the variable and shall return
EFI_INVALID_PARAMETER. 

So I think we probably need to fix the attributes to NV|RT|BS for both
this call and the one in query_variable_store. We should probably also
only do the workaround if the NV bit is set in the original query.

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