[U-Boot] [PATCH v3 4/4] tools: mkimage: Add: Kirkwood Boot Image support (kwbimage)

[Prafulla Wadaskar]

> -----Original Message-----
> From: Simon Kagstrom [mailto:simon.kagstrom at netinsight.net] 
> Sent: Friday, September 04, 2009 12:00 PM
> To: Prafulla Wadaskar
> Cc: u-boot at lists.denx.de; Ashish Karkare; Prabhanjan Sarnaik
> Subject: Re: [U-Boot] [PATCH v3 4/4] tools: mkimage: Add: 
> Kirkwood Boot Image support (kwbimage)
> 
> Hi Prafulla!
> 
> I see the complications and understand that it might be difficult to
> get it running.
Dear Simon
So we can keep this complex enhancement for future updates, keeping this patch simpler
 
> 
> On Thu, 3 Sep 2009 07:15:48 -0700
> Prafulla Wadaskar <prafulla at marvell.com> wrote:
> 
> > > I think it could also be useful to be able to produce 
> just the boot
> > > header without the U-boot image. For example if you want to place
> > > U-boot at some other location on the flash or (as a developer)
> > > frequently re-flash U-boot, but don't want to write to 
> the first block
> > > all the time (you only need to rewrite it when moving U-boot).
> >
> > This is not possible.
> > Boot Header is a part of Kirkwood boot image,
> > Header contains u-boot imagesize so for this, first block 
> need to be written each time.
> 
> Understandable. On the other hand, it should be possible to pad the
> U-boot image to some specific size to keep the size constant. 
> Typically
> to the erase size.
Again it would be problem it image size jumps over sector size boundary

> 
> > Secondly u-boot header is of 512bytes only whereas minimum 
> sector size could be 4kbytes (typical),
> > so rest part of first sector will be a waste.
> 
> I'd be prepared to waste a couple of bytes :-)
You will have to waste 128Kbytes-512bytes on sheevaplug :-)
Finally you will waste one extra sector (u-boot.kwb size is ~160kb)

> 
> > Also at the end of boot image checksum need to be 
> calculated on entire image including header.
> 
> This is not how I read the documentation. I thought the 
> 32-bit checksum
> is for the image only, not the headers? Anyway, if it does include the
> headers, then I see why this would be impossible.
Currently it is done in the way I explained with some reference,
I will do some exercise with your suggestions and let you know.

Regards..
Prafulla . .

> 
> 
> Thanks for the explanation!
> 
> // Simon
>