GNAT Linker Options & Memory Maps

GNAT Linker Options & Memory Maps

[Marin David Condic, 561.796.8997, M/S 731-93]

    After spending time doing the RTFM thing on the GNAT linker, I'm
    still left with a question that maybe someone can help me with:

    There appears to be no way of controlling the link map using the
    GNAT linker. (I did not recall seeing anything about an option to
    even print out the link map.) Is there any way of using the linker
    to control the addresses at which things fall? (Yes, I know Ada
    gives you an address clause for fixing things in memory. However,
    I have often failed to get the desired results using address
    clauses and there are times when it would be much more handy to
    use the linker to do this.)

    Also, I did not see any provisions for outputting a symbol table
    or for specifying a load image format other than the default host
    system format. (Motorola S-records, maybe?)

    I'm trying to find out how practical it would be to point GNAT at
    an embedded target, and I guess I'm discovering that it would take
    some work here at the link end as well as the compile end.

    MDC

Marin David Condic, Senior Computer Engineer     ATT:        561.796.8997
Pratt & Whitney GESP, M/S 731-96, P.O.B. 109600  Fax:        561.796.4669
West Palm Beach, FL, 33410-9600                  Internet:   CONDICMA@PWFL.COM
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Re: GNAT Linker Options & Memory Maps

[Robert Dewar]

Marin asks

<<    There appears to be no way of controlling the link map using the
    GNAT linker. (I did not recall seeing anything about an option to
    even print out the link map.) Is there any way of using the linker
    to control the addresses at which things fall? (Yes, I know Ada
    gives you an address clause for fixing things in memory. However,
    I have often failed to get the desired results using address
    clauses and there are times when it would be much more handy to
    use the linker to do this.)
 
    Also, I did not see any provisions for outputting a symbol table
    or for specifying a load image format other than the default host
    system format. (Motorola S-records, maybe?)
 >>

There is no such thing as "the GNAT linker", GNAT uses one of the standard
system linkers that are around, and has the capabilities you want if and
only if this linker has these capabilities. It is also quite straightforward
to change which linker you are using if necessary. But anyway, GNAT is using
standard system capabilities. When it comes to linking, if C can do it, then
so can GNAT.

Re: GNAT Linker Options & Memory Maps

[Kirk Beitz]

and to follow up on what robert says, the answer to your problem is
relatively straightforward (since he answered "YES" to your literal
question "Is there any way of using the linker ...?" but didn't really
tell you how):

using gnatmake as your tool to build with (which, after making sure that
all ada units in the dependency graph of your build are properly
compiled, will properly call  gnatbind and then the normal system
linker), simply use the -largs command to pass whatever arguments you
want to to the system linker.  this should be in TFM that you were
looking at, though perhaps not obvious.  just look for the help section
on gnatmake.

--Kirk

Robert Dewar wrote:
> 
> Marin asks
> 
> <<    There appears to be no way of controlling the link map using the
>     GNAT linker. (I did not recall seeing anything about an option to
>     even print out the link map.) Is there any way of using the linker
>     to control the addresses at which things fall? (Yes, I know Ada
>     gives you an address clause for fixing things in memory. However,
>     I have often failed to get the desired results using address
>     clauses and there are times when it would be much more handy to
>     use the linker to do this.)
> 
>     Also, I did not see any provisions for outputting a symbol table
>     or for specifying a load image format other than the default host
>     system format. (Motorola S-records, maybe?)
>  >>
> 
> There is no such thing as "the GNAT linker", GNAT uses one of the standard
> system linkers that are around, and has the capabilities you want if and
> only if this linker has these capabilities. It is also quite straightforward
> to change which linker you are using if necessary. But anyway, GNAT is using
> standard system capabilities. When it comes to linking, if C can do it, then
> so can GNAT.