Compiling with 32 bit Erlang on x86_64 doesn't work

[NAR]

Hello!

When I run 32 bit Erlang OTP R15B03 on x86_64, the compilation fails, because the fd_send.o and fd_recv.o objects are 32 bit files, while the procket.o is 64 bit, so the link phase returns with an error. The full output: ==> procket (compile) make: Entering directory /home/ethanl/titansimvolte/deps/procket/c_src' gcc -c -Wall -fPIC -g -O2 -m32 -DNDEBUG -DSPARE_SEND_FDS -DSPARE_RECV_FDS fd_send.c gcc -c -Wall -fPIC -g -O2 -m32 -DNDEBUG -DSPARE_SEND_FDS -DSPARE_RECV_FDS fd_recv.c ar cr libancillary.a fd_send.o fd_recv.o ranlib libancillary.a gcc -m32 -g -Wall -o ../priv/procket -L. procket_cmd.c -lancillary make: Leaving directory/home/ethanl/titansimvolte/deps/procket/c_src' Compiled src/procket_ioctl.erl Compiled src/procket_msg.erl Compiled src/procket_mktmp.erl Compiled src/packet.erl Compiled src/bpf.erl Compiled src/procket.erl Compiling c_src/procket.c /usr/lib64/gcc/x86_64-suse-linux/4.3/../../../../x86_64-suse-linux/bin/ld: skipping incompatible c_src/libancillary.a when searching for -lancillary /usr/lib64/gcc/x86_64-suse-linux/4.3/../../../../x86_64-suse-linux/bin/ld: cannot find -lancillary collect2: ld returned 1 exit status ERROR: cc c_src/procket.o -Lc_src -lancillary -shared -L/app/erlang/otp_R15B03/LMWP3/lib/erlang/lib/erl_interface-3.7.9/lib -lerl_interface -lei -o priv/procket.so failed with error: 1 and output: /usr/lib64/gcc/x86_64-suse-linux/4.3/../../../../x86_64-suse-linux/bin/ld: skipping incompatible c_src/libancillary.a when searching for -lancillary /usr/lib64/gcc/x86_64-suse-linux/4.3/../../../../x86_64-suse-linux/bin/ld: cannot find -lancillary collect2: ld returned 1 exit status

The following patch fixes the compilation on this platform: diff --git a/rebar.config b/rebar.config index 20f8470..f2a0dc3 100644 --- a/rebar.config +++ b/rebar.config @@ -1,5 +1,5 @@ {port_specs, [

• {"priv/procket.so", ["c_src/procket.c"]}

• {"x86_64", "priv/procket.so", ["c_src/procket.c"], [{env, "$PROCKET_CFLAGS"}]} ]}.

  {port_env, [

But breaks when 64 bit Erlang OTP R16B03 is used on x86_64.Something more clever is needed.

[msantos]

Thanks for tracking this down and the patch!

I used to run a 32-bit VM on Mac OS X and I remember this used to work. I think it worked because rebar sets a default environment on darwin but not on linux, like this:

     %% OS X Leopard flags for 64-bit
     {"darwin9.*-64$", "CFLAGS", "-m64 $CFLAGS"},
     {"darwin9.*-64$", "CXXFLAGS", "-m64 $CXXFLAGS"},
     {"darwin9.*-64$", "LDFLAGS", "-arch x86_64 $LDFLAGS"},

     %% OS X Snow Leopard, Lion, and Mountain Lion flags for 32-bit
     {"darwin1[0-2].*-32", "CFLAGS", "-m32 $CFLAGS"},
     {"darwin1[0-2].*-32", "CXXFLAGS", "-m32 $CXXFLAGS"},
     {"darwin1[0-2].*-32", "LDFLAGS", "-arch i386 $LDFLAGS"},

The first element of the tuple is a regex against the ERLANG_TARGET env var that rebar sets. You can see what is going on by running rebar -vvv compile. In my case, I have:

{"ERLANG_TARGET","R17A-x86_64-unknown-linux-gnu-64"}

I don't have a 32-bit VM installed at the moment. I'm compiling one now but I think something like this should work:

diff --git a/rebar.config b/rebar.config
index 20f8470..a389083 100644
--- a/rebar.config
+++ b/rebar.config
@@ -4,9 +4,10 @@

 {port_env, [
     {"LDFLAGS", "$LDFLAGS -Lc_src -lancillary"},
-    {"x86_64", "PROCKET_CFLAGS", "-m$(ERLANG_ARCH)"},
-    {"i686", "PROCKET_CFLAGS", "-m$(ERLANG_ARCH)"},
-    {"i386", "PROCKET_CFLAGS", "-m$(ERLANG_ARCH)"}
+    {"x86_64", "PROCKET_CFLAGS", "-m$ERLANG_ARCH"},
+    {"x86_64", "CFLAGS", "$CFLAGS -m$ERLANG_ARCH"},
+    {"i686", "PROCKET_CFLAGS", "-m$ERLANG_ARCH"},
+    {"i386", "PROCKET_CFLAGS", "-m$ERLANG_ARCH"}
     ]}.

 {pre_hooks, [

Some extra line noise in that patch because I removed the parentheses so the variable would expand on the command line.

[msantos]

So the 32-bit VM on x86_64 identifies itself as:

{"ERLANG_ARCH","32"},
{"ERLANG_TARGET","R16B03-1-i686-pc-linux-gnu-32"},

This should fix it:

diff --git a/rebar.config b/rebar.config
index 20f8470..b182707 100644
--- a/rebar.config
+++ b/rebar.config
@@ -4,9 +4,11 @@

 {port_env, [
     {"LDFLAGS", "$LDFLAGS -Lc_src -lancillary"},
-    {"x86_64", "PROCKET_CFLAGS", "-m$(ERLANG_ARCH)"},
-    {"i686", "PROCKET_CFLAGS", "-m$(ERLANG_ARCH)"},
-    {"i386", "PROCKET_CFLAGS", "-m$(ERLANG_ARCH)"}
+    {"x86_64", "PROCKET_CFLAGS", "-m$ERLANG_ARCH"},
+    {"i686", "PROCKET_CFLAGS", "-m$ERLANG_ARCH"},
+    {"i686", "CFLAGS", "$CFLAGS -m$ERLANG_ARCH"},
+    {"i686", "LDFLAGS", "-m$ERLANG_ARCH $LDFLAGS"},
+    {"i386", "PROCKET_CFLAGS", "-m$ERLANG_ARCH"}
     ]}.

 {pre_hooks, [

[msantos]

@NAR I pushed a change that should fix this issue. If you have still have problems, please re-open this issue. And if you have any other problems or questions, please feel free to let me know!

[NAR]

Thanks, the patch solved the problem for me, the compilation works with 32 and 64 OTPs.