[U-Boot-Users] Access global data from standalone application

[U-Boot-Users] Access global data from standalone application

[Shawn Jin]

Hi,

Is there any way to access global data defined in U-Boot from
standalone applications? For example, hello_world wants to access
flash_info[].

Regards,
-Shawn.

[U-Boot-Users] Access global data from standalone application

[Wolfgang Denk]

In message <c3d0340b05061715317273d9ae@mail.gmail.com> you wrote:
> 
> Is there any way to access global data defined in U-Boot from
> standalone applications? For example, hello_world wants to access
> flash_info[].

Be careful with your terms. It is trivial to access "global data"  in
SA apps as the GD pointer is passed in a register - but "Global Data"
in U-Boot is something which has nothing to do with flash_info[].

You can export and call in SA apps functions which perform operations
on flash_info[], but you cannot  access  flash_info[]  or  any  other
global variables directly.

Note that this is intentional.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
G's Third Law:             In spite of all evidence  to  the  contra-
ry,  the  entire  universe  is composed of only two basic substances:
magic and bullshit.
H's Dictum:                There is no magic ...

[U-Boot-Users] Access global data from standalone application

[Shawn Jin]

> > Is there any way to access global data defined in U-Boot from
> > standalone applications? For example, hello_world wants to access
> > flash_info[].
> 
> Be careful with your terms. It is trivial to access "global data"  in
> SA apps as the GD pointer is passed in a register - but "Global Data"
> in U-Boot is something which has nothing to do with flash_info[].

Well, what I meant is exported data. Thanks for the clarification. My
understanding is that the GD pointer points to gd_t. Those data inside
gd_t can be accessed trivially in SA apps, as you said.

> You can export and call in SA apps functions which perform operations
> on flash_info[], but you cannot  access  flash_info[]  or  any  other
> global variables directly.

Confused. How do SA apps perform operations on exported data without
accessing them? Could you elaborate a little bit? I want to write a SA
app to print the protection info of all flash banks. I know flinfo can
do that. I just do some experiments. ;)

Regards,
-Shawn.

[U-Boot-Users] Access global data from standalone application

[Wolfgang Denk]

Hello,

in message <c3d0340b05061717456bc12331@mail.gmail.com> you wrote:
> 
> > You can export and call in SA apps functions which perform operations
            ^^^^^^     ^^^^            ^^^^^^^^^
> > on flash_info[], but you cannot  access  flash_info[]  or  any  other
> > global variables directly.
> 
> Confused. How do SA apps perform operations on exported data without
> accessing them? Could you elaborate a little bit? I want to write a SA

By calling functions in the U-Boot code which use the data.

> app to print the protection info of all flash banks. I know flinfo can
> do that. I just do some experiments. ;)

Then just export and call the do_flinfo function.

Why reinvent the wheel or duplicate already existing code?

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
                                                      -- Isaac Asimov