[U-Boot] [Exynos 5250 Query] Smp Boot

[Simon Glass]

Hi,

You could try to cc whoever wrote the code. You can use git blame to find
out.

But it sounds like you are on the right track. I may be able to help, will
email tomorrow if so.

Regards,
Simon
 On Sep 16, 2013 8:26 PM, "MJ embd" <mj.embd at gmail.com> wrote:

> Reminder, Please can anyone respond
>
> On 9/16/13, MJ embd <mj.embd at gmail.com> wrote:
> > Hi,
> >
> > I was trying to understand the booting (till linux) on samsung exynos
> > 5250. As this is my first on ARM Cortex. I have a few questions, so
> > following is a step by step understanding and [Q] mentions the
> > question I am asking
> >
> > [1] At POR (Power on Reset) the Internal Boot rom code executes, and
> > checks the boot location and if it finds sd card, it copies 14k from
> > the sd card (which is u-boot-spl.bin) into iRAM.
> > [2] the internal boot rom branches pc to the entry point of spl at
> > __start (0x2023400)
> > [3] First instruction at __start is b reset.
> > [4] this takes the route reset | cpu_init_crit | low_level_init |
> first_cpu
> >
> > [Q 1] At this point what is the state of secondary core, is it held in
> reset
> > ?
> > As per  document, ""
> > "the secondary CPUs (CPU1, CPU2, and CPU3) execute a WFI instruction,
> > which is actually a loop that checks the value of SYS_FLAGS register."
> >
> > I couldnt find the SYS_FLAGS register in Cortex A15 manual, can some one
> > point.
> >
> > [Q 2] The secondary core until the point the boot core calls
> > smp_kick_secondary is just waiting in WFI.
> > [5] the smp_kick_secondary does the following
> >  (a) at the address SYSFLAGS_ADDR (0x2020000) which is not in spl but
> > above it, it write the b reset instruction and
> > (b) Issues a SGI to the secondary core
> >
> > [Q 3] Does this mean that secondary core is listening at address
> > 0x2020000, I couldnt find that in any document?
> >
> > [6] Supposedly it does and it starts executing the reset function,
> > secondary core would end up in enter_smp_pen.
> > [Q 4] I dont understand what  is trying to achieve here, Can some one
> > explain.
> >
> >
> > I am planning to pen down the complete boot sequence, all help
> appreciated.
> >
> > Thanks in advance.
> > mj
> >
>
>
> --
> -mj
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