[ECOS] a silly question about the __exception_handlers

Nick Garnett nickg@ecoscentric.com
Fri Nov 26 09:54:00 GMT 2004


"twomol" <twomol@bj1860.net> writes:

>  hello
>   
>  I use E7T to describe my question.On E7T,when reset ,the address of rom/flash bank0 is mapped from 0x0 to 0x2000000.
>  I use ecos configtool build a redboot.bin using E7T templet(ROM startup).At the begining of the file is the  __exception_handlers.
>  The first statment of the  file is :ldr pc,[pc, #24];0x20
>  The conetent in 0x20 is 0x1820040.If I burn the redboot.bin in the rom/flash bank0,the board reset,begin to execute the first  statment "ldr pc,[pc, #24]",then the value of PC become 0x1820040.But at this moment the address of 0x1820040 can't 
> be accessed,because the memory haven't be remaped.

According to the linker scripts for the E7T, ROM is meant to be at
0x1800000. There is also 128k reserved at the base of ROM for a boot
monitor, which presumably executes RedBoot. RedBoot is not set up to
run directly from the reset vector.

Take a look at the documentation:

http://ecos.sourceware.org/docs-latest/redboot/e7t.html

-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com/     The eCos and RedBoot experts


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