Re: [avr-gcc-list] Query regarding hard located variables

[Anton Erasmus]

Hello Scott,

The following C Code will put variable gTestVar into section 
"no_init". The relevent linker script commands you will need to put 
this section at a specific address, I do not know.

 int gTestVar __attribute__((section ("no_init");

Regards
    Anton

> Hello Anton,
> 
> Yes, this is the kind of thing that I am after. However I am unable to
> find any examples or doumentation on how to do this. Specifically, I
> cannot find examples or instructions on how to do this for a single
> variable (or even a single file... I can put the "magic" variable in a
> file on it's own).
> 
> Does anyone have an example that they can point me towards (or send)
> which shows how to put a variable or a file into a specific section in
> RAM?
> 
> 
> Kind Regards,
> 
> Scott
> 
> Anton Erasmus wrote:
> > 
> > Date sent:              Mon, 07 Jan 2002 13:33:05 +1100
> > From:                   Scott Finneran <address@hidden>
> > Organization:           Smart Container To:                    
> > avr-gcc-list <address@hidden> Subject:               
> > [avr-gcc-list] Query regarding hard located variables
> > 
> > > Hello All,
> > >
> > > I would have thought that the following would be a more commonly
> > > asked (and therefore answered) question. I can only assume that I
> > > am searching for the info in the wrong place or using the wrong
> > > keywords. If so, then I apologise in advance.
> > >
> > > I would like to know how to hard locate a variable using gcc
> > > and/or the gnu linker. The hardware that I am using has a number
> > > of memory mapped hardware registers. Obviously I would like to
> > > avoid having the linker drop variables into memory addresses where
> > > these registers live. It would also be nice to be able have
> > > variables (of my choosing) be located at these addresses. Of
> > > course the latter can be easily achieved with a pointer. Many
> > > commercial embedded compilers provide a compiler specific
> > > directive such as: eg int reg1 _at(0x4000);
> > >
> > > Others simply allow you to specify the location of specific
> > > variables in linker scripts.
> > >
> > > I have seen many websites and articles (eg from embedded.com) talk
> > > about doing this. Many more say that it is possible. None of them
> > > (that I have found) say how, or even better give an example.
> > >
> > > Can anyone point me to some info or alternatively show me how this
> > > is done?
> > >
> > 
> > Hi,
> > 
> > You can put each variable in it's own named section with the
> > "attribute section" command of gcc. In your linker script you can
> > define the address of each section. I am not sure how many sections
> > the linker can handle.
> > 
> > Regards
> >    Anton
> avr-gcc-list at http://avr1.org
> 


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