[ECOS] Re: ROMRAM question

[Grant Edwards <grante at visi dot com>]

On 2006-12-04, dirk husemann <hud@zurich.ibm.com> wrote:

>> The question I have is this: is there an 'easy' way (i.e built
>> into the config tool perhaps) of not copying certain areas of
>> my application into SDRAM?

I don't know of any way using ecosconfig.

> don't include the firmware images with the application?
> instead store them in separate flash partitions or in JFFS2?

That sounds like a bit of a hassle.

I assume that the ROMRAM startup code only copies sections it
knows about a-priori, so any user-defined sections that were
added to the elf file without the HAL's knowledge will sit it
ROM and not be copied. 

There are three options I can think of for putting your data
into the image in a user-defined section so that it doesn't get
copied into RAM by the ROMRAM startup code:

 1. You can use __attribute__((section="secname")) to store
    things in user-defined linker sections, you'll have to
    modify the linker script to place the user-defined sections
    in ROM.  I don't think this is going to be easy.

 2. You can use objcopy to add a user-defined section to an elf
    file (or simplay create an elf file containing a
    user-defined section).

 3. You can use the --add-section and --add-section-flags
    linker flags to add a user-defined section to an elf file.

Make sure the "progbits" flag on the section is set to indicate
that you want the section in the hex file.

I think options 2 and 3 will need to done on the application
elf file _after_ it's been linked and before it's converted to
hex.

-- 
Grant Edwards                   grante             Yow!  Can you MAIL a BEAN
                                  at               CAKE?
                               visi.com            


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