[ECOS] NEWBIE: Memory Layout on AEB-1 Rev B

[ECOS] NEWBIE: Memory Layout on AEB-1 Rev B

[k e]

Hi,
I'm need all the room in RAM that I can get
on the AEB-1 Rev B.
Can someone tell me what the following lines
in the memory layout files are for?


file: mlt_arm_aeb_ram.ldi
...
    __reserved_vectors = 0; . = __reserved_vectors + 0x1000;
    __reserved_not_mapped = ALIGN (0x1); . = __reserved_not_mapped + 0x7000;
    __reserved_for_rom = ALIGN (0x1); . = __reserved_for_rom + 0x4000;
...

file: mlt_arm_aeb_ram.h
...
extern char CYG_LABEL_NAME (_reserved_vectors) [];
#define CYGMEM_SECTION_reserved_vectors (CYG_LABEL_NAME (_reserved_vectors))
#define CYGMEM_SECTION_reserved_vectors_SIZE (0x1000)
extern char CYG_LABEL_NAME (_reserved_not_mapped) [];
#define CYGMEM_SECTION_reserved_not_mapped (CYG_LABEL_NAME (_reserved_not_mapped))
#define CYGMEM_SECTION_reserved_not_mapped_SIZE (0x7000)
extern char CYG_LABEL_NAME (_reserved_for_rom) [];
#define CYGMEM_SECTION_reserved_for_rom (CYG_LABEL_NAME (_reserved_for_rom))
#define CYGMEM_SECTION_reserved_for_rom_SIZE (0x4000)
...

file: mlt_arm_aeb_ram.mlt
...
section reserved_vectors 1000 1 0 0 1 1 1 1 0 0 reserved_not_mapped reserved_not_mapped !
section reserved_not_mapped 7000 1 0 0 0 1 0 1 reserved_for_rom reserved_for_rom !
section reserved_for_rom 4000 1 0 0 0 1 0 1 rom_vectors rom_vectors !
section rom_vectors 0 4 0 1 0 1 0 1 text text !
...


Specifically,
the actual code section (text) starts at 0x0C000.
I'd like to shove this down in memory to use up
any room that I can.  Or at least know what goes into
the "reserved_not_mapped", etc sections so that I
can shrink the size of any memory that's not used.
FYI, I don't use GDB at all.  If any of this
space if for GDB stuff, then I'm ok losing that space.
FYI, I'm using ecos-1.3.1
I'd like to stay with that since I have stuff working
rather than spend time thrashing around with the CVS
image.

If what I'm asking makes sense, please provide an 
example of what I'd need to change in the above
files before re-configuring ecos.

Again, what I'm after is more usable RAM.
And learning what all these sections are for would
be nice too.
As you can probably tell, I'm REALLY new to the ld
process.

Thanks a bundle for any help you can provide.

The Gipp

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Re: [ECOS] NEWBIE: Memory Layout on AEB-1 Rev B

[Jonathan Larmour]

k e wrote:
> 
> Hi,
> I'm need all the room in RAM that I can get
> on the AEB-1 Rev B.
> Can someone tell me what the following lines
> in the memory layout files are for?
> 
> file: mlt_arm_aeb_ram.ldi
> ...
>     __reserved_vectors = 0; . = __reserved_vectors + 0x1000;

Used for the vectors. You can't avoid this unless you never intend to have
any interrupts or exceptions ever.

>     __reserved_not_mapped = ALIGN (0x1); . = __reserved_not_mapped + 0x7000;

There's no memory in the memory map here.

>     __reserved_for_rom = ALIGN (0x1); . = __reserved_for_rom + 0x4000;

If you don't intend to use the GDB stubs for debugging, you could remove
this. Also note that exception handlers will still have been set up by the
GDB stub in ROM, and those handlers will use RAM in this area. So if you
get any exceptions it will scribble in this area anyway. So obviously
either don't get any exceptions, or supply new exception handlers in your
app.

Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine

Re: [ECOS] NEWBIE: Memory Layout on AEB-1 Rev B

[k e]

sorry in advance if this starts a new thread.

--- Jonathan Larmour <jlarmour@redhat.com> wrote:
[snip]
> >     __reserved_for_rom = ALIGN (0x1); . = __reserved_for_rom + 0x4000;
> 
> If you don't intend to use the GDB stubs for debugging, you could remove
> this. Also note that exception handlers will still have been set up by the
> GDB stub in ROM, and those handlers will use RAM in this area. So if you
> get any exceptions it will scribble in this area anyway. So obviously
> either don't get any exceptions, or supply new exception handlers in your
> app.
[snip]

If I were to try this, is it as easy as removing the line for this
block of ram from the .h, .mlt, and .ldi files and then re-build ecos?
I'd assume that the subsequent sections would then map down by 0x4000
in memory.

ke

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Re: [ECOS] NEWBIE: Memory Layout on AEB-1 Rev B

[Jonathan Larmour]

k e wrote:
> 
> sorry in advance if this starts a new thread.
> 
> --- Jonathan Larmour <jlarmour@redhat.com> wrote:
> [snip]
> > >     __reserved_for_rom = ALIGN (0x1); . = __reserved_for_rom + 0x4000;
> >
> > If you don't intend to use the GDB stubs for debugging, you could remove
> > this. Also note that exception handlers will still have been set up by the
> > GDB stub in ROM, and those handlers will use RAM in this area. So if you
> > get any exceptions it will scribble in this area anyway. So obviously
> > either don't get any exceptions, or supply new exception handlers in your
> > app.
> [snip]
> 
> If I were to try this, is it as easy as removing the line for this
> block of ram from the .h, .mlt, and .ldi files and then re-build ecos?
> I'd assume that the subsequent sections would then map down by 0x4000
> in memory.

I believe so.

Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine