[U-Boot] Relocating to my code.

[U-Boot] Relocating to my code.

[prathika]

hi everyone,
I am working on a card based on PPC440EP, I am porting u-boot on this card.
As I understand, the PPC initially boots from the flash and then 
relocates itself to RAM address where there is board_init_r() and 
main_loop() is called.

I have an application code that simply does a loop back on UART 
channel2. After all the initialization,
I want to knock off the relocation code, board_init_r() and main_loop() 
execution in u-boot and relocate it to my application
The application code will residing in flash. How can I do this.... 
anyone kindly help me in this regard...........

Regards,
Prathika R

[U-Boot] Relocating to my code.

[Detlev Zundel]

Hi Prathika,

> hi everyone,
> I am working on a card based on PPC440EP, I am porting u-boot on this card.
> As I understand, the PPC initially boots from the flash and then 
> relocates itself to RAM address where there is board_init_r() and 
> main_loop() is called.

Correct.  Running from flash makes writing to flash (i.e. updating
images there) somewhat complicated.

> I have an application code that simply does a loop back on UART 
> channel2. After all the initialization,
> I want to knock off the relocation code, board_init_r() and main_loop() 
> execution in u-boot and relocate it to my application
> The application code will residing in flash. How can I do this.... 
> anyone kindly help me in this regard...........

Why do you want to run from flash - what exactly are you trying to do?
Did you think about the consequences, i.e. where will your code store
local variables, etc.?

Why do you want to use U-Boot in the first place if you do not want to
use its main functionality?

Cheers
  Detlev

-- 
The  mathematician's patterns,  like the  painter's or  the poet's,  must be
beautiful;  the ideas, like the colours or the words, must fit together in a
harmonious way. Beauty is the first test: there is no permanent place in the
world for ugly mathematics.                       -- G. H. Hardy
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de

[U-Boot] Relocating to my code.

[Detlev Zundel]

Hi Prathika,

> I did not mean it should run from flash itself..My application will
> just reside in flash, I will read back from flash to a RAM location.

To be honest, I have trouble understanding this.

> As I understand, in board_init_f(), after calling the init_sequence,
> relocate_code() is called and it is a must to call relocate_code(),
> from where it branches to main_loop().  My aim is to branch to my
> application code before calling relocate_code().My application code's
> executable address is 0x40004.

Well, if you are working on a PowerPC platform, then 0x40004 is
certainly a RAM address.

> Is it that i can just give jump to 0x40004 before calling
> relocate_code() and it works?

I still don't get why you want to change *anything* inside U-Boot.  Why
not just use the commands that are available in the command line
interpreter?  Say you have your application stored at fc2e0000
(arbitrary address) and it is 64k in size.  Then why not just do:

cp.b fc2e0000 40000 10000;go 40004

Setting bootenv to these commands will start your application on U-Boot
timeout.  Sticking them into preboot even runs them before the command
line is started at all.

Cheers
  Detlev

-- 
 Those who do not understand Unix are condemned to reinvent it,
 poorly.
 - Henry Spencer, University of Toronto Unix hack
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de

[U-Boot] Relocating to my code.

[prathika]

Detlev Zundel wrote:
> Hi Prathika,
>
>   
>> I did not mean it should run from flash itself..My application will
>> just reside in flash, I will read back from flash to a RAM location.
>>     
>
> To be honest, I have trouble understanding this.
>
>   
>> As I understand, in board_init_f(), after calling the init_sequence,
>> relocate_code() is called and it is a must to call relocate_code(),
>> from where it branches to main_loop().  My aim is to branch to my
>> application code before calling relocate_code().My application code's
>> executable address is 0x40004.
>>     
>
> Well, if you are working on a PowerPC platform, then 0x40004 is
> certainly a RAM address.
>
>   
>> Is it that i can just give jump to 0x40004 before calling
>> relocate_code() and it works?
>>     
>
> I still don't get why you want to change *anything* inside U-Boot.  Why
> not just use the commands that are available in the command line
> interpreter?  Say you have your application stored at fc2e0000
> (arbitrary address) and it is 64k in size.  Then why not just do:
>
> cp.b fc2e0000 40000 10000;go 40004
>
> Setting bootenv to these commands will start your application on U-Boot
> timeout.  Sticking them into preboot even runs them before the command
> line is started at all.
>
>   
--Thanks for your reply Detley. I think I was just trying to complicate 
things.I have got a better picture now.
Before calling relcoate_code() in board.c, ifI using the command

"cp.b fc2e0000 40000 10000;go 40004"  should be fine.....

Thanks & Regards,
Prathika R

[U-Boot] Relocating to my code.

[Detlev Zundel]

Hi Prathika,

> --Thanks for your reply Detley. I think I was just trying to complicate
> things.I have got a better picture now.
> Before calling relcoate_code() in board.c, ifI using the command

Uhm, well, actually you should not touch U-Boot code at all.  It should
simply work.

> "cp.b fc2e0000 40000 10000;go 40004"  should be fine.....

Don't forget to substitute fc2e0000 with the address for your setup ;)

Cheers
  Detlev

-- 
Irrationality is the square root of all evil.
                                     -- Douglas Hofstadter
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de