Re: [ECOS] ROM-startup RedBoot can't load RAM-startup RedBoot

[Gary Thomas <gary at mlbassoc dot com>]

Grant Edwards wrote:
> I've built ROM-startup and RAM-startup versions of RedBoot for
> the NIOS2 architecture.  When loaded into RAM via JTAG, the
> RAM-startup version works fine. The ROM-startup verions works
> fine (except that it erases itself anytime it tries to write to
> flash).
>
> What I can't seem to be able to do is to use RedBoot in ROM to
> load the RAM-startup version of RedBoot.  I think it's because
> the text section in the RAM-startup version loads on top of the
> running ROM-startup RedBoot's ".rwdata" section.
>
> Is that the way things are supposed to work?

No.  The RAM 'mlt*' files are normally organized such that their
requirements (TEXT, DATA, etc) are outside what might be used by
a ROM (or ROMRAM) RedBoot.

Try looking at some PowerPC platform:
MEMORY
{
    ram : ORIGIN = 0x0000000, LENGTH = 0x8000000 // 128MB
    rom : ORIGIN = 0xf0000000, LENGTH = 0x04000000
}

SECTIONS
{
    SECTIONS_BEGIN
    CYG_LABEL_DEFN(__reserved_vectors) = 0; . = CYG_LABEL_DEFN(__reserved_vectors) + 0x3000;
    CYG_LABEL_DEFN(__reserved_vsr_table) = ALIGN (0x10); . = CYG_LABEL_DEFN(__reserved_vsr_table) + 
0x200;
    CYG_LABEL_DEFN(__reserved_virtual_table) = ALIGN (0x10); . = 
CYG_LABEL_DEFN(__reserved_virtual_table) + 0x100;
    CYG_LABEL_DEFN(__reserved_for_rom) = ALIGN (0x10); . = CYG_LABEL_DEFN(__reserved_for_rom) + 
0x7cd00;
    SECTION_vectors (ram, ALIGN (0x10), LMA_EQ_VMA)
    SECTION_text (ram, ALIGN (0x4), LMA_EQ_VMA)
    SECTION_fini (ram, ALIGN (0x4), LMA_EQ_VMA)
    SECTION_rodata1 (ram, ALIGN (0x8), LMA_EQ_VMA)
    SECTION_rodata (ram, ALIGN (0x8), LMA_EQ_VMA)
    SECTION_fixup (ram, ALIGN (0x4), LMA_EQ_VMA)
    SECTION_gcc_except_table (ram, ALIGN (0x1), LMA_EQ_VMA)
    SECTION_data (ram, ALIGN (0x8), LMA_EQ_VMA)
    SECTION_sbss (ram, ALIGN (0x4), LMA_EQ_VMA)
    SECTION_bss (ram, ALIGN (0x10), LMA_EQ_VMA)
    CYG_LABEL_DEFN(__heap1) = ALIGN (0x8);
    SECTIONS_END
}

In this case the physical RAM starts at 0x0, but the lines labeled
__reserved_XXX show what memory should not be used.  The actual image
will be built following this area.  This method also allows for [crude]
sharing of data between the two environments, e.g. exception handlers,
virtual vector tables, etc.

> Here is the memory map for the ROM-startup version:
>
> Idx Name          Size      VMA       LMA       File off  Algn
>   0 .entry        00000020  00000000  00000000  000000b4  2**2
>                   CONTENTS, ALLOC, LOAD, READONLY, CODE
>   1 .exceptions   0000002c  00000020  00000020  000000d4  2**2
>                   CONTENTS, ALLOC, LOAD, READONLY, CODE
>   2 .text         0001f39c  0000004c  0000004c  00000100  2**2
>                   CONTENTS, ALLOC, LOAD, READONLY, CODE
>   3 .rodata       00004fb0  0001f3e8  0001f3e8  0001f49c  2**2
>                   CONTENTS, ALLOC, LOAD, READONLY, DATA
>   4 .rom_monitor_rwdata 00000108  08000000  00024398  0002444c  2**0
>                   ALLOC
>   5 .rwdata       00000f88  08000108  000244a0  0002444c  2**2
>                   CONTENTS, ALLOC, LOAD, CODE
>   6 .bss          00020158  08001090  08001090  000253d4  2**4
>                   ALLOC
>
> And here is the memory map for the RAM-startup version:
>
> Idx Name          Size      VMA       LMA       File off  Algn
>   0 .entry        00000000  00000000  00000000  000000d4  2**2
>                   CONTENTS, ALLOC, LOAD, READONLY, CODE
>   1 .exceptions   00000000  00000020  00000020  00023e60  2**0
>                   CONTENTS
>   2 .rom_monitor_rwdata 00000108  08000000  08000000  000000d4  2**0
>                   ALLOC
>   3 .text         0001deac  08000108  08000108  000000d4  2**2
>                   CONTENTS, ALLOC, LOAD, READONLY, CODE
>   4 .rodata       00004f9c  0801dfb4  0801dfb4  0001df80  2**2
>                   CONTENTS, ALLOC, LOAD, READONLY, DATA
>   5 .rwdata       00000f44  08022f50  08022f50  00022f1c  2**2
>                   CONTENTS, ALLOC, LOAD, CODE
>   6 .bss          00020094  08023ea0  08023ea0  00023e60  2**4
>                   ALLOC


--
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

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