[U-Boot] [PATCH 1/6] sniper: Move PXE file address to a viable location

[Paul Kocialkowski]

Le samedi 26 mars 2016 à 14:59 -0400, Tom Rini a écrit :
> On Sat, Mar 26, 2016 at 12:19:59PM +0100, Paul Kocialkowski wrote:
> > 
> > This moves the PXE file address out of the bounds of the U-Boot image (which
> > is
> > loaded at 0x80100000).
> > 
> > This also moves the ramdisk address to a better-looking aligned location.
> > 
> > Signed-off-by: Paul Kocialkowski <contact at paulk.fr>
> > ---
> >  include/configs/sniper.h | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/configs/sniper.h b/include/configs/sniper.h
> > index 171a8c4..2598af1 100644
> > --- a/include/configs/sniper.h
> > +++ b/include/configs/sniper.h
> > @@ -243,8 +243,8 @@
> >  	"loadaddr=0x82000000\0" \
> >  	"fdt_addr_r=0x88000000\0" \
> >  	"fdtaddr=0x88000000\0" \
> > -	"ramdisk_addr_r=0x88080000\0" \
> > -	"pxefile_addr_r=0x80100000\0" \
> > +	"ramdisk_addr_r=0x84000000\0" \
> > +	"pxefile_addr_r=0x86000000\0" \
> >  	"scriptaddr=0x80000000\0" \
> >  	"bootm_size=0x10000000\0" \
> >  	"boot_mmc_dev=0\0" \
> I strongly discourage these locations.  Quoting myself from
> ti_armv7_common.h:
> /*
>  * We setup defaults based on constraints from the Linux kernel, which should
>  * also be safe elsewhere.  We have the default load at 32MB into DDR (for
>  * the kernel), FDT above 128MB (the maximum location for the end of the
>  * kernel), and the ramdisk 512KB above that (allowing for hopefully never
>  * seen large trees).  We say all of this must be within the first 256MB
>  * as that will normally be within the kernel lowmem and thus visible via
>  * bootm_size and we only run on platforms with 256MB or more of memory.
>  */

Thanks for the clarification, I think the addresses make sense as they are then.

> Now, have you actually run into a problem with overwriting U-Boot?

Actually, I had forgotten that U-Boot relocates. This address only caught my eye
as being equal to CONFIG_SYS_TEXT_BASE when going through the header, but I
didn't investigate enough.

There is indeed no run-time problem, thanks to relocation. I'll simply drop
these patches.

> Since U-Boot will run-time relocate, this shouldn't be a problem in
> practice?  The minor games we play with locations here are due to Falcon
> Mode where the BSS in question here is the one for SPL and we don't want
> those two to conflict.

-- 
Paul Kocialkowski, low-level free software developer on embedded devices

Website: https://www.paulk.fr/
Coding blog: https://code.paulk.fr/
Git repositories: https://git.paulk.fr/ https://git.code.paulk.fr/
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