[ECOS] more redboot questions, please help...really lost

[<xinumike-newsgroup at yahoo dot com>]

I hope somebody might be able to help a bit more.
I am still trying to get redboot going on a powerpc
platform, and I admit that sometimes I am not the
sharpest knife in the drawer.

I am using the Viper as a base.  

I build redboot 3 ways.  ROM, RAM, and ROMRAM.
I can burn redboot into my flash and step through
it with the bdm.

Questions:

1) ROMRAM: How does the memory remap work?  I see this
code fragment:

#ifdef CYG_HAL_STARTUP_ROMRAM
// Need to set the PC into the FLASH (ROM) before the
address map changes
        lwi     r3,10f
        lwi     r5,0xFE000000
        or      r3,r3,r5
        mtctr   r3
        bctr

Perhaps I am not understanding the whole picture, but
how does the make the program counter happy?

2) ROM: If I run in the ROM only mode, is the address
remapping still done?   I don't see code to related
to modifying the PC in this case.   If we step
through from reset to hal_hardware_init, won't
the program counter think that it is somewhere off
of 0, so when we modify chip select 0, won't we
go off into the weeds?  

3) I am still confused about how to manipulate the
memory map.   Should my ROM code be generated to
execute starting at 0xfe000000? 

Thanks for any help.
-Mike

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