[U-Boot] [PATCH v2 4/4] ARM: fix CONFIG_SPL_MAX_SIZE semantics

[Albert ARIBAUD]

Hi Stephen,

On Wed, 10 Apr 2013 17:09:45 -0600, Stephen Warren
<swarren at wwwdotorg.org> wrote:

> On 04/10/2013 04:50 PM, Albert ARIBAUD wrote:
> > On Wed, 10 Apr 2013 16:21:54 -0600, Stephen Warren wrote:
> >> On 04/09/2013 05:14 PM, Albert ARIBAUD wrote:
> ...
> >> This still seems to have separate defines for SPL text/data/rodata size
> >> and BSS size. If I want instead to limit the total text/data/rodata/bss
> >> size, but place no specific limit on the bss size individually, can I
> >> not do that?
> > 
> > This would defeat the purpose of giving CONFIG_SPL_MAX_SIZE a constant
> > meaning -- one of the issues which prompted this patch series is that
> > in ARM sometime CONFIG_SPL_MAX_SIZE meant BSS included, and sometime
> > excluded, and this inconsistency had to be resolved. As in the rest of
> > U-boot, CONFIG_SPL_MAX_SIZE was meant BSS excluded, this is the
> > semantics that was decided.
> > 
> > What we could do, though, is subdivide testing based on the existence or
> > non-existence of CONFIG_SPL_BSS_START_ADDR:
> > 
> > - if CONFIG_SPL_BSS_START_ADDR exists, then we assume SPL image and
> >   BSS are disjoint and we test each one against its max size, as this
> >   patch series does;
> > 
> > - if CONFIG_SPL_BSS_START_ADDR does not exist, then we assume SPL image
> >   and BSS are contiguous and we test the whole of SPL against the sum
> >   of CONFIG_SPL_MAX_SIZE and CONFIG_SPL_BSS_MAX_SIZE.
> 
> Why not either:
> 
> a) define CONFIG_SPL_MAX_SIZE to include the BSS size if
> CONFIG_SPL_BSS_START_ADDR is not set, but exclude it if it is.

That was in my original proposals, and it was spoken against:
<http://article.gmane.org/gmane.comp.boot-loaders.u-boot/158073>
<http://article.gmane.org/gmane.comp.boot-loaders.u-boot/158094>

> or:
> 
> b) use 3 defines instead of 2, so that CONFIG_SPL_MAX_SIZE (if defined)
> always limits text+rodata+data, CONFIG_SPL_MAX_FOOTPRINT (if defined)
> always limits text+rodata+data+bss, and CONFIG_SPL_BSS_MAX_SIZE (if
> defined) always limits bss size.
> 
> Tegra would define only CONFIG_SPL_MAX_FOOTPRINT in this scheme.
> Other boards would presumably define other combinations of those.

That is a possibility, with the minor nitpick that we could possibly
end up having conflicting values for the three symbols, whereas with
the CONFIG_SPL_BSS_START_ADDR solution, there can be no value conflict.

Amicalement,
-- 
Albert.