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

[Simon Glass]

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?

Regards,
Simon