Re: gcc, crt0, and linker scripts...

["Russ.Shaw" <russell at webaxs dot net>]

Hi,

My last reply i sent last night bounced after 5 hours.

I got it all to compile and link now :)

I found that the source for crt0.S is in:
  newlib-1.8.2/newlib/libc/sys/h8300hms/crt0.S

The last error i was getting was that the _end symbol in some
C libraries remained undefined. I found that this was defined
in the supplied linker scripts:

/usr/local/h8300-hms/lib/ldscripts/h8300h.x
                                   h8300h.xbn
                                   h8300h.xn
                                   h8300h.xr
                                   h8300h.xu

So i added _end to my own script, and voila, no errors :)

I'll check that _nostartfiles option to see whether i need it for
the separate ld command. gcc and binutils are quite impressive after
one gets the hang of it :)


Doug Evans wrote:
> 
>  > However, what does gcc use for a linker script? I need to tell
>  > gcc about my eprom memory map etc.
> 
> It uses these:
> 
>  > /usr/local/h8300-hms/lib/ldscripts/h8300h.x
>  >                                    h8300h.xbn
>  >                                    h8300h.xn
>  >                                    h8300h.xr
>  >                                    h8300h.xu
> 
>  > I could get gcc to use my own script using -Wl,T<myscript>, but
>  > i'll still get linker errors because the output section names
>  > need to be compatible with the supplied crt0 start-up file.
>  >
>  > I can't use my own startup file, because the standard C libraries
>  > refer to symbols such as _end in crt0.o.
> 
> Maybe take the source for newlib's crt0.o
> (newlib/libc/sys/h8300hms/crt0.S), and munge it with your crt0.S
> to achieve something usable?
> 
> When linking, specify your crt0.o and -nostartfiles.
> 
>  > So what is the 'normal' procedure for configuring a cross-gcc to
>  > custom hardware?
> 
> In general, it's always the same (just as you have already done).
> There's no trick (in general) to configuring the gnu tools
> for custom hardware.  The trick comes at link time.
> You need to write your own linker script (and maybe crt0) and
> work out the right args to pass to gcc (or ld) when you link.
> 
> Keep at it, you're almost there. :-)

-- 
*******************************************
*   Russell Shaw, B.Eng, M.Eng(Research)  *
*      email: russell@webaxs.net          *
*      Australia                          *
*******************************************

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