Re: [ECOS] Memory Layout

[Gary Thomas <gthomas at cambridge dot redhat dot com>]

On 19-Apr-2001 james chen wrote:
>>
>> On 18-Apr-2001 james chen wrote:
>> > Hello,
>> >
>> >        From memory layout, I find that Redboot( startup in ROM) and
>> > Applications( startup in RAM ) both share the same memory address and
> size.
>> > When I use GDB debugging applications through redboot's gdb stub. Will
>> > redboot's memory  be cracked by Applications? Thanks in advance!
>>
>> Memory used by RedBoot and "normal" applications do not overlap.  The MLT
>> files imply that they do, but this is because RedBoot is just a ROM
>> application and the MLT setup is to allow for any application to use all
>> available resources.
>>
>> In general, RedBoot uses a chunk of low memory (128k is typical) and
>> RAM based applications are set up to load just above that and use the
>> remaining memory.
>>
>        After looking many ARM based platform in eCos. RAM based applications
> leave different size memory( from 0x8000--0x20000), I think these memory is
> used by RedBoot except vectors( sure?:-) ). Which size will I leave memory
> for RedBoot, I am using my custom board based on ARM7TDMI.
>        Another quesiton, when I release my applications and RedBoot will not
> ship in. Will the memory used by redboot be lost( can't used by normal
> applicationss). If then, how can I re-use it?

If your application is to run in RAM, then you should leave things as is.
There *will* be a monitor of some sort, even if it is not RedBoot, and it will
require memory to run.  We have carved out the space up to 0x20000 for this.

If your application runs in ROM, then there is no problem as it will have
access to all of RAM.

Question: if you are building a custom board and shipping a bundled application
with it, why would you _not_ want RedBoot, even in the final product?