Cross linking dynamic executables

Cross linking dynamic executables

[Andrew STUBBS]

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When cross compiling a dynamic executable, the linker attempts to find
the dynamic linker in the 'standard places' (just as it does when
compiling nativly). This behaviour is rather irritating when the linker
tries to link an SH object file (in my case) against the x86 dynamic
linker on the build system.

I do not know whether my solution is acceptable to other people, but I
have attached a patch which attempts to solve the problem. It makes much
more sense to me that the linker should look for cross dynamic linkers
in the same place it looks for cross dynamic libraries. If it does not
find it with the libraries it still continues to look in the standard
places.

-- 
Andrew Stubbs
andrew.stubbs@st.com
(aka. andrew.stubbs@superh.com)

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2004-12-15  Andrew Stubbs  <andrew.stubbs@st.com>

	* emultempl/elf32.em (gld*_after_open): Search for the dynamic linker in
	the library search path (as opposed to the 'standard' places) when cross
	compiling.

--- src/ld/emultempl/elf32.em	2004-11-22 20:33:33.000000000 +0000
+++ src/ld/emultempl/elf32.em	2004-12-14 11:33:23.000000000 +0000
@@ -880,8 +880,20 @@
 	    {
 	      char *filename;
 
+EOF
+if [ "x${host}" = "x${target}" ] ; then
+# When cross compiling the dynamic linker is unlikly to be in
+# the standard place - especially if the binutils were built and
+# then moved to somewhere else. In this case the best thing to do
+# is look for the dynamic linker in the same place as the libraries.
+# If compiling natively ignore the -L options on the command line
+# and always used the normal places.
+cat >>e${EMULATION_NAME}.c <<EOF
 	      if (search->cmdline)
 		continue;
+EOF
+fi
+cat >>e${EMULATION_NAME}.c <<EOF
 	      filename = (char *) xmalloc (strlen (search->name) + len + 2);
 	      sprintf (filename, "%s/%s", search->name, l->name);
 	      nn.name = filename;

Re: Cross linking dynamic executables

[Daniel Jacobowitz]

On Wed, Dec 15, 2004 at 02:36:06PM +0000, Andrew STUBBS wrote:
> When cross compiling a dynamic executable, the linker attempts to find
> the dynamic linker in the 'standard places' (just as it does when
> compiling nativly). This behaviour is rather irritating when the linker
> tries to link an SH object file (in my case) against the x86 dynamic
> linker on the build system.
> 
> I do not know whether my solution is acceptable to other people, but I
> have attached a patch which attempts to solve the problem. It makes much
> more sense to me that the linker should look for cross dynamic linkers
> in the same place it looks for cross dynamic libraries. If it does not
> find it with the libraries it still continues to look in the standard
> places.

This is inconsistent with the rest of the rpath/rpath-link handling,
IIRC.

I recommend you try --with-sysroot, which should change where we search
for the dynamic linker.

-- 
Daniel Jacobowitz

RE: Cross linking dynamic executables

[Andrew STUBBS]

> I recommend you try --with-sysroot, which should change where 
> we search
> for the dynamic linker.

That doesn't do what I require. At least not quite. Not without changing
where I keep things anyway.

However, if you feel that my patch is not suitable then that's fine. I can
always use it locally (till I find a better way). I didn't really expect
this one to go anywhere. It's just something I've found useful.

Thanks

Andrew