[ECOS] Relocating RedBoot from ROM to RAM after....

[ECOS] Relocating RedBoot from ROM to RAM after....

[Prasad, Siva]

Hi,

Can RedBoot be configured to boot from ROM and then relocate itself to RAM
and execute from RAM then on. 
We can configure RedBoot to completely boot either from RAM or ROM during
build time, but we need it to boot from ROM and continue in RAM.

This is for our custom board. Size of flash is 32MB on our board, where as
the 80310 (XSCALE) supports only 8MB of flash. So, we need to do bank
switching in software. This poses a constraint on the boot loader to be
running from RAM, in order to load Linux and other images from 32MB flash.

Can we build RedBoot to relocate after starting?. Can RAM version be
modified to fit this requirement.. if so, can some one show me the pointers
on how to.

Thanks,
Siva Prasad.

Re: [ECOS] Relocating RedBoot from ROM to RAM after....

[Andrew Lunn]

On Fri, Jul 13, 2001 at 11:50:18AM -0700, Prasad, Siva wrote:
> Hi,
> 
> Can RedBoot be configured to boot from ROM and then relocate itself to RAM
> and execute from RAM then on. 

In principal, there is no reason Redboot should not work ROMRAM
startup. This is something i spent a little time on trying to get
working, but failed so far due to lack of time.

Your message implies you are using the Xscale processors. Thats a
StrongARM? If so look back in the email archives for a patch and tar
file that make the PID board ROMRAM start. Use this is an
example. First implement ROMRAM start for plain applications. I choose
the tm_basic test program. Once you have plain programs ROMRAM
starting you can then make RedBoot ROMRAM start. There is very little
that needs changing. You just have to make sure the virtual vector
stuff is setup correctly, and fiddle with the memory map. Lastly you
then need to modify the memory map for normal applications. Your
Redboot will be using more RAM, so you have to modify the memory map
of the application to take this into account.

If you get this working, please post patches back to the list. IMHO,
this is something that Redboot should do. There is a big problem with
redboot running in ROM. You cannot use the rest of the flash for
anything else. Redboot will take control every so often and if there
is a flash operation going on at that time, eCos will crash. ROMRAM
redboot solves this problem.

        Andrew