[ECOS] RedBoot necessary for porting ecos?

[Ilija Kocho]

Hi Mike and Lukas

Some comments on RedBoot.



On 11.01.2013 05:33, Michael Jones wrote:
> Lukas,
>
> I just went through the newbie problems, so I'll give some advice. I am not an expert, but I can tell you my thoughts based on my newbie experience.
>
> RedBoot is basically a program that runs in the target device's flash, and loads an application over some serial device and then becomes a GDB server. In this case, RedBoot is an eCos application just like the application you are debugging.
>
> The issues with using RedBoot are that the application being debugged can corrupt RedBoot, and RedBoot uses up memory that the application could use. I managed to get this to work on a K60, which is also CortexM3, but eventually I decided to use a JTAG debugger instead. I found the experience using JTAG much better. However, if you need to debug over an ethernet, RedBoot could do it.

RedBoot usability can be, indeed, limited by memory constrains. On
single chip systems with about 128KiB RAM it is possible to run and even
debug eCos application under RedBoot, but the application size will be
severely limited, because a part of RAM is allocated by RedBoot itself.

But there are other examples such as TWR-K70F120M, a system with 128MiB
external RAM where memory constrain is no issue and RedBoot debugging
runs smoothly. Even more, in order to load the application into external
memory you need initialization of DDRAM controller, which requires
initialised clock - a tedious work for JTAG. On the other hand when
running/debugging from RedBoot you start with initialised clock and
DDRAM controller.

Ilija


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