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Re: eCos in RAM


>>>>> "Daniel" == Daniel Andersson <Daniel.Andersson@combitechsystems.com> writes:

    Daniel> I am having some trouble to get eCos to work in RAM on my
    Daniel> mpc850. Currently i run eCos in flash and that works fine.
    Daniel> What are the steps i need to take for my applikation to
    Daniel> work in RAM? Do i have to have a ROM monitor installed
    Daniel> when my application runs in RAM?

This depends entirely on the hardware. Normally you need some code in
ROM, either your application or suitable firmware such as RedBoot,
which the processor starts running on reset. If you already have eCos
running in flash then using RedBoot for the firmware should be easy
enough. Then you need to set up your platform HAL package to support a
RAM startup, which means primarily setting up the various files
related to the memory map so that the application code lives in RAM
rather than ROM. For example, where you currently have an
mlt_xxx_rom.ldi you will now also need a suitable mlt_xxx_ram.ldi. Add
a suitable startup and custom build steps to the HAL configury, and
you can now build RAM applications that can be downloaded via gdb and
RedBoot. There may also be some startup code which is no longer
relevant because RedBoot will have done much of the hardware
initialization already, and that can be ifdef'd out for RAM startups.

There are alternative approaches which do not involve firmware, e.g.
using something like JTAG to download the application into RAM and set
the PC. However using firmware like RedBoot is more common.

Bart

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