[U-Boot] ref:fail to include stdio.h

[Paul Wang]

Hi, Wolfgang,
I am trying to port some code of xyssl to u-boot in order to do the
digital signature verification.
Unfortunately, xyssl uses some stdlib functions, which are related to
file operations, strings, malloc and free (I worry these most). 
The existing SHA1 features work fine with xscale. The main issue of
digital signature verification on u-boot is the large integer
operations.

Regards.

Paul Wang.

-----Original Message-----
From: Wolfgang Denk [mailto:wd at denx.de] 
Sent: Thursday, February 26, 2009 7:15 PM
To: Paul Wang
Cc: u-boot at lists.denx.de
Subject: Re: [U-Boot] ref:fail to include stdio.h

Dear Paul,

In message
<FE00509E242C6145AA57855D449BE2182A19D4 at server.Tectonica.local> you
wrote:
> 
> The problem is: When I want to add any one of std header files
anywhere
> on my architecture (pxa270), the compiler complains: stdio.h: No such
> file or directory.

U-Boot is not a standard application that runs  under  control  of  a
general  purpose  OS,  but  it's  a  boot loader that lives in a very
restricted, simple environment. As such, we cannot use the standard C
library (glibc).  Instead,  U-Boot  is  self-contained  and  includes
everything it needs, and nothing more.

<stdio.h> is a header file that is provided by glibc - it  cannot  be
used  with  U-Boot  as  U-Boot doesn't provide the context needed for
such a complex library like glibc.


I'm not sure why you would want to include  <stdio.h>  -  it  is  not
needed in U-Boot context. Please look around in the existing code how
things are set up in U-Boot. This is NOT like developing a user space
application  under Linux. It is even more restricted than programming
Linux kernel code (and  in  Linux  kernel  code  you  cannot  include
<stdio.h> either).

Best regards,

Wolfgang Denk

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