[U-Boot] [PATCH v3 0/9] Add a pre-relocation malloc() implementation

[Tom Rini]

On Wed, Jul 23, 2014 at 06:24:08AM -0600, Simon Glass wrote:
> Hi,
> 
> On 14 July 2014 18:16, Simon Glass <sjg at chromium.org> wrote:
> > Hi Tom,
> >
> > On 14 July 2014 16:28, Tom Rini <trini at ti.com> wrote:
> >>
> >> On Thu, Jul 10, 2014 at 10:23:24PM -0600, Simon Glass wrote:
> >>
> >> > There has been talk on and off of a pre-relocation malloc() implementation.
> >> > Driver model needs this so that it can work before relocation.
> >> >
> >> > A previous implementation was sent in a v1 series.
> >> >
> >> > This implementation works by allocating space on the stack. The benefit is
> >> > that boards do not need to specify the address of the malloc() area, only
> >> > the size. The down-side is that due to the way board_init_f() is called,
> >> > architecture-specific code needs to be used to allocate the space.
> >> >
> >> > No clever algorithms are used to allocate space, free() is a nop and
> >> > realloc() is not supported. This fits well with the desire to avoid wasting
> >> > space on bucket tables and the hassle of supporting BSS data before
> >> > relocation. We don't expect 'churn' in the pre-relocation case - we just
> >> > want to allocate small amounts of memory temporarily.
> >> >
> >> > After relocation a new malloc() pool is created and the old one is lost,
> >> > although pointers into it will survive the immediate process of relocation.
> >> >
> >> > Implementations are provided for sandbox and arm (32-bit only).
> >> >
> >> > A related change is made to the early init for each arch to make this work.
> >>
> >> My concern without a fix right now is how to make use of this in SPL,
> >> when we're able to move SPL over to using still more generic code rather
> >> than re-inventing the board_init_{f,r} wheels, in the case where we init
> >> DRAM.
> >
> > One option would be to split this new code out into a separate file,
> > and have two malloc() implementations:
> >
> > - big one - falls back to small one pre-relocation
> > - small one - used for SPL
> 
> I'm thinking of applying this to the dm repo now, except for the arm
> patches where I would like to get Albert's ack (so I'll wait a few
> more days).
> 
> Any objections?

I think we'll be OK.  I checked over the callpath again on OMAP parts
and we setup DDR prior to _main (in SPL) so we'll be fine.

-- 
Tom
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