How can I start different programs from flash.

I want to update the software over a serial HDLC link.

My own bootloader at address 0x0000 in flash is not allowed

to be overwritten. This bootloader is a normal C-program with drivers for

HDLC etc.

Therefore it's not possible to use the NIOS II Flash programmer.

My own bootloader can receive files in S-RECORD format.

to download a program in another flash region,

I changed the address of the normal .flash file

(Resetvector from SOPC was 0x000000(flash) and compiler settings

are "program memory (.text) = ext ram")

with

"nios2-elf-objcopy -I srec -O srec --srec-forceS3 --srec-len 32

--change-addresses 0x200000 ext_flash.flash ext2_flash.flash"

My bootloader stored the program, which should normally be at flash address

0x000000, at flash address 0x200000.

Then i made a simple

asm("call 0x200000");

in my bootloader program and the new program seams to start ok.

It seems that the small altera bootloader in front of the program

is not disturbed by the address shift ???

I don't know if this is a good solution for making software updates and if it

works correctly in every case ?

Also how can I make the asm call variable ?