[U-Boot-Users] stand alone application

[kow9loon]

Thank you for the reply and the direction. I am a novice in U_boot, though I
have some prior experience in working on other boot codes.

There is still another outstanding question that I would like to raisie,
however. In the Standalone-README file, it states that for PowerPC, the load
adress is 0x00040000, and the start address is 0x00040004. On the board that
I am working on, those two addresses aren't available. Is that a way for me
to have the load address and the start address to be RELOCATED to addresses
that fall within the aforementioned range? Any comment would be greatly
welcomed. Thanks.

Best Regards,

Kow9loon










wd wrote:
> 
> In message <9771147.post at talk.nabble.com> you wrote:
>> 
>> I am trying to write a stand alone application, which is supposed to be a
>> board diagnostics for manufacturing. The way it supposes to work is as
>> follows: U_boot could either download the diagnostics manually under the
>> U_boot prompt, or be calling up do_tftp() directly if it is to be done
>> automatically. Results generated from the diagnostics are to be recorded
>> in
>> the RAM, whose contents shall later be uploaded as a log file to an
>> external
>> server via tftp. After reading the examples provided in the example
> 
> I recommend to use the existing log device; note that it is
> compatible with Linux's syslog mechanism.
> 
>> (1) In my understanding, the stand alone application (the board
>> diagnostic
>> for manufacturing) is supposed to be compiled as a separately entity in
>> the
> 
> Yes.
> 
>> U-boot path and then be placed in an external server, waiting to be
>> downloaded to the RAM on board; when either go <address> or
>> do_go(address)
> 
> You can also store it in flash memory, or on some storage device, of
> course.
> 
>> is executed, control get passed to the stand alone application, how could
>> the stand alone application be able to make calls to functions that are
>> exported (those appeared in both exports.c and export.h), without some
>> kind
>> of "linking"? Unless go <address> or do_go(address) perform some sort of
> 
> This is documented in the doc/README.standalone file; no linking is
> done.
> 
>> "linking" or "peudo linking" action, this doesn't sound possible. Could
>> someone explain to me how this works? 
> 
> The keyword is: jump table.
> 
>> My expectation of how this could work is: on execution of the go
>> <address>
> 
> Why don't you simply read the documentation instead of speculating?
> 
>> command or do_go (address), address of the jump table is to be loaded
>> into a
>> register, and it is the responsibility of the application to save the
>> value
>> of this register before anything else, in such a way to allow the
>> application to call up functions that it elects by picking up the correct
>> addresses of these functions via indexing. However, after reading the
>> examples provided in U-boot, I have not seen any motion of saving the
>> value
>> of the register. However, vwhich register U-boot chooses to use would be
>> processor dependent. This is just my two cents.
> 
> You should RTFM.
> 
>> (2) Is uploading currently being supported in U-boot's tftp
>> implementation?
> 
> No.
> 
> Best regards,
> 
> Wolfgang Denk
> 
> -- 
> DENX Software Engineering GmbH, HRB 165235 Munich, CEO: Wolfgang Denk
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