Re: [ECOS] RedBoot ROM resource management after loading RAM eCos application.

[Andrew Lunn <andrew at lunn dot ch>]

On Tue, Feb 21, 2006 at 12:43:11AM +0100, Reginald Deschrijver wrote:
> Hello all,
> 
> I am having a question regarding the RedBoot ROM package.
> 
> I have an ARM7TDMI board and I want to use RedBoot ROM to load my eCos .elf
> applications into RAM, execute, and debug using GDB.
> 
> I know that RedBoot ROM still uses a little bit of RAM to operate, but when
> RedBoot has downloaded the RAM application and executes this application,
> does the eCos application have the full RAM (with the exception of the fixed
> virtual vector table) available for it?
> I.e. does RedBoot still use RAM even when my eCos application is running?

Yes, it needs some RAM. Normally redboot provides the hal diag tty
communication channel, gdb talks to redboot, etc. It needs RAM to do
this. The linker script is setup so that Redboot gets the lowest part
of RAM and the application is loaded above this. eg

mlt_arm_ebsa285_ram.ldi

// eCos memory layout - Tue Sep 05 16:58:21 2000

// This is a generated file - do not edit

#include <cyg/infra/cyg_type.inc>

MEMORY
{
    ram : ORIGIN = 0, LENGTH = 0x1000000
}

SECTIONS
{
    SECTIONS_BEGIN
    SECTION_fixed_vectors (ram, 0x20, LMA_EQ_VMA)
    SECTION_rom_vectors (ram, 0x30000, LMA_EQ_VMA)
    SECTION_text (ram, ALIGN (0x4), LMA_EQ_VMA)
    SECTION_fini (ram, ALIGN (0x4), LMA_EQ_VMA)

You can see that the RAM application uses RAM from 0x30000 upwards.

        Andrew

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