Re: [PATCH] Modify UEFI anti-bricking code

From: joeyli <jlee@suse.com>
To: Matthew Garrett <matthew.garrett@nebula.com>
Cc: Matt Fleming <matt@console-pimps.org>,
	"Fleming, Matt" <matt.fleming@intel.com>,
	"rja@sgi.com" <rja@sgi.com>,
	"mingo@kernel.org" <mingo@kernel.org>,
	"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
	"bp@alien8.de" <bp@alien8.de>,
	"jkosina@suse.cz" <jkosina@suse.cz>,
	"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"hpa@linux.intel.com" <hpa@linux.intel.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"oneukum@suse.de" <oneukum@suse.de>
Subject: Re: [PATCH] Modify UEFI anti-bricking code
Date: Thu, 06 Jun 2013 10:24:20 +0800	[thread overview]
Message-ID: <1370485460.6523.30.camel@linux-s257.site> (raw)
In-Reply-To: <1370448519.6315.36.camel@x230.lan>

於 三，2013-06-05 於 16:08 +0000，Matthew Garrett 提到：
> 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:
> 

The patch I tested on OVMF, it can delete DUMMY object when system boot.

> 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@srcf.ucam.org

Yes, I think that more safe for fix the attributes.

Thanks a lot!
Joey Lee