[U-Boot] [U-Boot, 1/4] cam_enc_4xx: fix CONFIG_SPL_MAX_SIZE semantics

[Albert ARIBAUD]

Hi Heiko,

On Tue, 09 Apr 2013 08:50:26 +0200, Heiko Schocher <hs at denx.de> wrote:

> Hello Tom,
> 
> Am 08.04.2013 22:43, schrieb Tom Rini:
> > On Mon, Apr 08, 2013 at 09:58:26AM -0000, Albert ARIBAUD wrote:
> > 
> >> CONFIG_SPL_MAX_SIZE wrongly included BSS size. Split
> >> max size between image and BSS based on sizes reported
> >> for current build.
> >>
> >> Signed-off-by: Albert ARIBAUD <albert.u.boot at aribaud.net>
> >>
> >> ---
> >> board/ait/cam_enc_4xx/u-boot-spl.lds |    2 +-
> >>  include/configs/cam_enc_4xx.h        |    4 +++-
> >>  2 files changed, 4 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/board/ait/cam_enc_4xx/u-boot-spl.lds b/board/ait/cam_enc_4xx/u-boot-spl.lds
> >> index dd9d52d..25625dc 100644
> >> --- a/board/ait/cam_enc_4xx/u-boot-spl.lds
> >> +++ b/board/ait/cam_enc_4xx/u-boot-spl.lds
> >> @@ -25,7 +25,7 @@
> >>   */
> >>  
> >>  MEMORY { .sram : ORIGIN = CONFIG_SPL_TEXT_BASE,\
> >> -		LENGTH = CONFIG_SPL_MAX_SIZE }
> >> +		LENGTH = (CONFIG_SPL_MAX_SIZE + CONFIG_SPL_BSS_MAX_SIZE) }
> >>  
> >>  OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
> >>  OUTPUT_ARCH(arm)
> >> diff --git a/include/configs/cam_enc_4xx.h b/include/configs/cam_enc_4xx.h
> >> index 56528dd..df3682b 100644
> >> --- a/include/configs/cam_enc_4xx.h
> >> +++ b/include/configs/cam_enc_4xx.h
> >> @@ -230,7 +230,9 @@
> >>  #define CONFIG_SPL_STACK		(0x00010000 + 0x7f00)
> >>  
> >>  #define CONFIG_SPL_TEXT_BASE		0x00000020 /*CONFIG_SYS_SRAM_START*/
> >> -#define CONFIG_SPL_MAX_SIZE		12320
> >> +/* SPL max size is 12K -- but --pad-to requires a single decimal number */
> >> +#define CONFIG_SPL_MAX_SIZE		12288
> >> +#define CONFIG_SPL_BSS_MAX_SIZE		(4*1024)
> > 
> > This is wrong, you've just increased the overall limit to 16K.  I know
> > there's a reason that current limit is so exact, Heiko?  And also, this
> 
> The cam_enc_4xx use only 12k for the SPL code. This is defined in the
> UBL header, see u-boot:doc/README.davinci.nand_spl, but can be adapted
> for this board. The SoC has an IRam of 32K - ~2k for RBL stack, see:
> 
> http://www.ti.com/lit/gpn/tms320dm368
> 
> I have no access anymore to this HW to do some tests :-( so I looked
> into the hexdump of the current u-boot code with your patch applied, and
> the code on the interesting borders (0x0, 0x800 and 0x3800) looks good
> to me ...
> 
> > shows the conceptual problem I have (and 2/2 has the same, along with
> > tegra).  The important limit is the combined size.  It doesn't matter if
> > it's 11K text/data/rodata and 1K BSS, or 8+4.  When using custom linker
> > scripts, we avoid this and can just comment overall (which would need
> > adding here) that we only care about the combined size.  But then tegra
> > would be wrong since it uses the generic arm spl linker script?

Thanks Heiko.

I'd read about the SoC IRAM, and had chosen 16K indeed arbitrarily but
taking care not to use most of it -- half felt like safe enough.
However, I'd missed the UBL thing, thanks for pointing this out. So
either I keep 12K, split for instance 10K and 2K (5 pages and 1 page),
or I reaise the number of pages in board/ait/cam_enc_4xx/ublimage.cfg,
correct?

Let us assume I keep 12K. Here is a current build of cam_enc_4xx:

text  data   bss   dec  hex filename
439526  13148  311092  763766  ba776  ./u-boot
  9073	  840     500	10413   28ad  ./spl/u-boot-spl

And the map file gives __start = 0x20, __bss_start = 0x26e0, and
__bss_end = __image_copy_end = _end = 0x28d4, which makes the
size of the non-BSS part of the image equal to 9952 bytes (thus below
10K) and the BSS part size is 500 bytes, below 2K.

So, it seems I could just replace

#define CONFIG_SPL_MAX_SIZE		12288
#define CONFIG_SPL_BSS_MAX_SIZE		(4*1024)

with

#define CONFIG_SPL_MAX_SIZE		10240
#define CONFIG_SPL_BSS_MAX_SIZE		(2*1024)

and keep the UBL cfg file untouched -- any future size issue with
image or BSS size would imply changing these values and uptating the
UBL cfg file.

Would that be ok?

> bye,
> Heiko

Amicalement,
-- 
Albert.