[U-Boot] 83xx fails to boot with moderately sized kernels

[Stefan Roese <sr@denx.de>]

Hi Ira & Wolfgang,

On Friday 10 September 2010 13:18:55 Wolfgang Denk wrote:
> > Does anyone know the true maximum value for CONFIG_SYS_BOOTMAPSZ on Linux
> > (if one even exists)?
> 
> The CONFIG_SYS_BOOTMAPSZ thing is as old as U-Boot and PPCBoot
> exists, i. e. well over a decade. IIRC there was such a limitation on
> the then current 2.2.13 Linux kernels, at least on MPC8xx and PPC40x
> systems, which is where all started from.
> 
> 
> I am pretty sure that as long as nobody ran into any problems, nobody
> looked into that code, so it was copied from architecture to
> architecture without much thinking, if any.

I looked at it a bit over a year ago and commited this change for the AMCC/APM 
eval boards:

commit 6942efc2be1b90054fa4afa5cda7023469fe08b9
Author: Stefan Roese <sr@denx.de>
Date:   Tue Jul 28 10:50:32 2009 +0200

    ppc4xx: amcc: Set CONFIG_SYS_BOOTMAPSZ to 16MB for big kernels
    
    This patch changes CONFIG_SYS_BOOTMAPSZ from 8MB to 16MB which is the
    initial TLB on 40x PPC's in the Linux kernel. With this change even bigger
    Linux kernels (> 8MB) can be booted.
    
    This patch also sets CONFIG_SYS_BOOTM_LEN to 16MB (default 8MB) to enable
    decompression of bigger images.
    
    Signed-off-by: Stefan Roese <sr@denx.de>


So we have this 16MiB initial TLB restriction at least for PPC405 (not 
PPC440). I'm pretty sure that 83xx has no such tight restrictions.

Cheers,
Stefan

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