Re: Changing memory segments

[Jose Ramirez <joseramirez_00 at yahoo dot com>]

This sounds like an interesting problem that I may
have to deal with in the near future...

Question:

Why the focus on slower speeds on the ROM? I was under
the assumption that if the BSP is configured properly,
FLASH access (I assume you are using FLASH for ROM?)
time differentials are handled by the OS bsp or CPU.
This sounds interesting, maybe you could clear that up
for me.

What's your CPU? Is it over 2 years old?

Another, 
Are you using registers for improved performance on
top of this?

--- Stan Katz <stan@ctc-control.com> wrote:
> Is there any way to change the default segments used
> by the compiler. I am
> working on an embedded system with several types of
> ROM and RAM (Internal
> and External - different speeds, static Ram and
> DRAM, etc.) and am often
> shuffling code and data into specific memory regions
> for improved
> performance.
> 
> Currently I have 2 ways of doing this, one is a set
> of preprocessor macros
> that set the section attribute e.g. 
> 
> #define SLOWROM __attribute__ ((section
> (".slowrom")))
> 
> and I set the attributes (segments)of functions and
> variables individually
> and make sure that they are handled properly in my
> link script. 
> I also use the link script to force all the code or
> data from a particular
> file into a memory region.
> 
> The problem is that I need to have a different link
> script for every
> different configuration and any changes to the files
> needs to change not
> only the makefile but also the link script. Ideally
> I would like to have a
> single link script for each hardware version and
> handle the software options
> in the makefile only.
> 
> I can see two ways of doing this, the easiest would
> be to be able to change
> the segments used by the compiler, either with
> command line options or with
> a utility that took an object file and renamed
> segments, e.g. change the
> .text segment to be .fastrom or .code, etc. Then I
> could configure the
> makefile to generate the correct segments in the
> object file to be linked.
> However I can't find such a utility and I'm not sure
> how easy it would be to
> write.
> 
> Alternatively, if I could use macros in the linker
> file, I could use a
> common include file to define the groups of object
> modules for both the
> makefile and the linker and then specify the files
> to be forced into a
> memory region using the macro, however this would
> need significant changes
> to the linker.
> 
> Any suggestions ?
> 
> TIA
> Stan Katz
> 
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