linux-kernel - Re: [PATCH] x86, efi: initial the local variable of DataSize to zero

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Date:	Mon, 29 Apr 2013 18:34:28 +0800
From:	joeyli <jlee@...e.com>
To:	matt.fleming@...el.com
Cc:	mjg59@...f.ucam.org, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Matthew Garrett <mjg@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86, efi: initial the local variable of DataSize to
 zero

於 一，2013-04-29 於 18:25 +0800，joeyli 提到：
> 於 六，2013-04-27 於 01:19 +0800，Lee, Chun-Yi 提到：
> > That will be better initial the value of DataSize to zero for the input of
> > GetVariable(), otherwise we will feed a random value. The debug log of input
> > DataSize like this:
> > 
> > ...
> > [  195.915612] EFI Variables Facility v0.08 2004-May-17
> > [  195.915819] efi: size: 18446744071581821342
> > [  195.915969] efi:  size': 18446744071581821342
> > [  195.916324] efi: size: 18446612150714306560
> > [  195.916632] efi:  size': 18446612150714306560
> > [  195.917159] efi: size: 18446612150714306560
> > [  195.917453] efi:  size': 18446612150714306560
> > ...
> 
> After applied patch, the log of size like this:
> 
> [   82.442042] EFI Variables Facility v0.08 2004-May-17
> [   82.442202] efi: size: 0
> [   82.442360] efi:  size': 1039
> [   82.443828] efi: size: 0
> [   82.444127] efi:  size': 2616
> [   82.447057] efi: size: 0
> [   82.447356] efi:  size': 5832
> [   82.452669] efi: size: 0
> [   82.453128] efi:  size': 1
> [   82.454339] efi: size: 0
> [   82.454843] efi:  size': 1
> [   82.456173] efi: size: 0
> [   82.456764] efi:  size': 8
> [   82.458194] efi: size: 0
> [   82.458905] efi:  size': 4
> 
> The size' is the return value of Acer BIOS, it return right size value
> then we feed zero DataSize.
^^^^^^^^^ when 

Sorry for typo!
Joey Lee

> 
> 
> Thanks a lot!
> Joey Lee
> 
> > 
> > Found on Acer Aspire V3 BIOS, it will not return the size of data if we input a
> > non-zero DataSize.
> > 
> > Cc: Matthew Garrett <mjg@...hat.com>
> > Cc: Matt Fleming <matt.fleming@...el.com>
> > Cc: H. Peter Anvin <hpa@...or.com>
> > Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
> > ---
> >  arch/x86/platform/efi/efi.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> > index e4a86a6..cb59732 100644
> > --- a/arch/x86/platform/efi/efi.c
> > +++ b/arch/x86/platform/efi/efi.c
> > @@ -204,7 +204,7 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
> >  	}
> >  
> >  	if (boot_used_size && !finished) {
> > -		unsigned long size;
> > +		unsigned long size = 0;
> >  		u32 attr;
> >  		efi_status_t s;
> >  		void *tmp;
> 
> 
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