linux-kernel - Re: [Fastboot] [CFT] ELF Relocatable x86 and x86

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Date:	Mon, 7 Aug 2006 13:44:39 -0400
From:	Don Zickus <dzickus@...hat.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	fastboot@...l.org, Horms <horms@...ge.net.au>,
	Jan Kratochvil <lace@...kratochvil.net>,
	"H. Peter Anvin" <hpa@...or.com>,
	Magnus Damm <magnus.damm@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [Fastboot] [CFT] ELF Relocatable x86 and x86_64 bzImages

On Sat, Aug 05, 2006 at 10:07:01AM -0600, Eric W. Biederman wrote:
> Don Zickus <dzickus@...hat.com> writes:
> 
> >> The length error comes from lib/inflate.c 
> >> 
> >> I think it would be interesting to look at orig_len and bytes_out.
> >> 
> >> My hunch is that I have tripped over a tool chain bug or a weird
> >> alignment issue.
> >
> > I thought so too, but I took vmlinuz images from people (Vivek) who had it
> > boot on their systems but those images still failed on my two machines.  
> >
> >> 
> >> The error is the uncompressed length does not math the stored length
> >> of the data before from before we compressed it.  Now what is
> >> fascinating is that our crc's match (as that check is performed first).
> >> 
> >> Something is very slightly off and I don't see what it is.
> >
> > I printed out orig_len -> 5910532 (which matches vmlinux.bin)
> >              bytes_out -> 5910531
> >
> >> 
> >> After looking at the state variables I would probably start looking
> >> at the uncompressed data to see if it really was decompressing
> >> properly.  If nothing else that is the kind of process that would tend
> >> to spark a clue.
> >
> > I am not familiar with the code, so very few sparks are flying.  I'll
> > still dig through though.  Thanks for the tips.
> 
> I guess the interesting thing to do would be to 
> - Recompute the crc to see if we still match.
> - Possibly instrument of flush_window.
> 
> I have a strange feeling that the uncompressed data is getting corrupted
> after we have flushed the window.

It seems to be an AMD64 vs EM64T problem.  AMD chipsets work but Intel
chipsets don't.  

I also blindly incremented bytes_out (as a really cheap hack), it didn't
work until I added some random putstr's below it (timing??).  Then the
kernel booted. 

Still looking into things.  

Cheers,
Don

> 
> Eric
> 
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