[U-Boot] Early malloc() summary

[Marek Vasut]

Dear Graeme Russ,

> Hi Marek,
> 
> On 08/15/2012 12:00 AM, Marek Vasut wrote:
> > Dear Graeme Russ,
> > 
> >> Hi Marek,
> >> 
> >> On Tue, Aug 14, 2012 at 10:37 PM, Marek Vasut <marex at denx.de> wrote:
> >>> Dear Tomas Hlavacek,
> >>> 
> >>>> Hello Marek,
> >>>> 
> >>>> On Sun, Aug 12, 2012 at 1:16 AM, Marek Vasut <marex at denx.de> wrote:
> >>>>> So ... we should aim for firing up the real mallocator as soon as
> >>>>> possible and maybe implement discontigmem (sparsemem) into it, so we
> >>>>> don't have to bother with relocating pointers maybe?
> >>>>> 
> >>>>> The only problem I see is platforms where the memory disappears.
> >>>> 
> >>>> I doubt that on ARM for instance you can set off real mallocator that
> >>>> early without completely rewriting it.
> >>> 
> >>> Esp. on ARM, I won't see much of a problem. You usually have some small
> >>> SRAM where such allocator could run.
> >>> 
> >>>> The idea of having one complex
> >>>> mallocator working in the same manner in board_init_f and board_init_r
> >>>> stages, being able to operate on all platforms using their nifty
> >>>> memory-management/model features
> >>> 
> >>> Do you need them? You usually need only a piece of RW memory.
> >>> 
> >>>> and being seamless to users is really
> >>>> tempting. But do we need/want to introduce such deep rewrites?
> >>> 
> >>> Deep rewrites? You'd only need to implement sparsemem into it, which
> >>> might be list of RW memory areas instead of one memory area.
> >> 
> >> OK, stop right there (please) - This gets into a highly architecturally
> >> specific implementations of malloc. Let's not go there OK :)
> > 
> > Not really, today you give the mallocator one slab of memory on which it
> > operates ... making it so it'd operate on a list of such slabs shouldn't
> > be _that_ hard.
> 
> When you start throwing around "discontigmem", "sparsemem" and "nifty
> memory-management/model features" you are talking architecture specifics

In uboot, not so much ... in uboot it'd be just a matter of making one memory 
are that's currently available to malloc() into list of memory areas and that's 
all. Not specific at all


Best regards,
Marek Vasut