[coreboot] [PATCH] LAR: Don't clobber top 8 bytes

Stefan Reinauer stepan at coresystems.de
Wed Dec 3 23:02:42 CET 2008

On 03.12.2008, at 19:00, Jordan Crouse <jordan at cosmicpenguin.net> wrote:

> Carl-Daniel Hailfinger wrote:
>> On 03.12.2008 12:48, Stefan Reinauer wrote:
>>> Carl-Daniel Hailfinger wrote:
>>>> LAR currently overwrites the top 13 bytes (0xfffff3-0xffffff) of  
>>>> the
>>>> bootblock with zeros, then it stores the ROM size in  
>>>> 0xfffff4-0xfffff7.
>>>> The top 8 bytes are unused in that scheme.
>>>> Leave the top 8 bytes as they are and allow us to store something  
>>>> in
>>>> there during the bootblock build process. The byte at 0xfffff3 is  
>>>> 0xff
>>>> by default on x86 and setting it to 0 is not needed.
>>>> Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net 
>>>> >
>>> Nack.
>>> They're unused, and until they are used, they should be cleared to a
>>> consistent state.
>> They are already cleared by arch/x86/stage0_common.S. Having to clear
>> them in the LAR would mean the code in stage0_common.S is crap and  
>> needs
>> to be fixed.
> Not necessarily.  This is a userland utility, so there is no real  
> penalty for making extra sure that the area is in a valid state.   
> LAR shouldn't depend on the v3 code to do the right thing, nor  
> should the v3 code depend on LAR to do the right thing.

In fact the area is not completely clean due to the binutils  
workaround. We had "nicer" code there, and it broke on Ron's binutils,  
so we went to the current version. It works, so don't waste time  
fixing it.


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