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

[MJ embd]

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