Re: [sodaville] [RFC] [PATCH V2] Adding DTB to architecture independent vmlinux

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

On Thu, Oct 28, 2010 at 06:35:55PM +0200, Sebastian Andrzej Siewior wrote:
> H. Peter Anvin wrote:
> >How big are these blobs in the typical case?  Padding to the page
> >size
> You usually pad the dtb by 1kib (-p 1024 in dtc). Converting all dtbs in
> powerpc's tree leads to:
>  991545 / 130 = 7627 bytes average.

If you're folding a whole batch of dtbs into the kernel, doing the
1kib padding on each is probably not sensible.  The padding is so that
tweaks to the dtb which require expansion can be done easily, but if
you're relocating the dtb anyway, you can allocate more space at that
time, with fdt_open_into().

That would bring the average size down to 6603 bytes (-p 1024 is "1024
bytes of extra space", not "expand to a 1024 byte boundary").

-- 
David Gibson			| I'll have my music baroque, and my code
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