On 5/24/2016 11:11 AM, Christian Ehrhardt wrote:

Hi Panu,
I already agreed to Thomas on IRC but won't have time until next week.
Thanks for making a patch that does that already - I'll give it a look and
some test on my end next week then.



Christian Ehrhardt
Software Engineer, Ubuntu Server
Canonical Ltd

On Tue, May 24, 2016 at 11:56 AM, Panu Matilainen [off-list ref]
wrote:

quoted

On 05/20/2016 08:08 PM, Thomas Monjalon wrote:

quoted

2016-05-20 18:50, Christian Ehrhardt:

quoted

The individual libraries have various cross dependencies.
This is already refelcted in the DEPDIR dependency, but not yet in
proper DT_NEEDED flags in the .so's.
This adds the -l flags so that is properly stored in the .so's ELF
headers.

Why not filling LDLIBS by parsing DEPDIRS-y in rte.lib.mk?

A fair question :) The thought has passed my mind too, but I thought it'd
be too messy with differing library vs directory names and other
exceptions. But in reality manually maintained separate LDLIBS is only
going to get out of sync sooner or later, and turns out its not that bad
anyway:

diff --git a/mk/rte.lib.mk b/mk/rte.lib.mk
index b420280..88b4e98 100644
--- a/mk/rte.lib.mk
+++ b/mk/rte.lib.mk

@@ -77,6 +77,12 @@ else
 _CPU_LDFLAGS := $(CPU_LDFLAGS)
 endif

+# Translate DEPDIRS-y into LDLIBS
+IGNORE_DEPS = -lrte_eal/% -lrte_net -lrte_compat
+_LDDIRS = $(subst librte_ether,libethdev,$(DEPDIRS-y))
+_LDDEPS = $(subst lib/lib,-l,$(_LDDIRS))
+LDLIBS += $(filter-out $(IGNORE_DEPS), $(_LDDEPS))
+
 O_TO_A = $(AR) crDs $(LIB) $(OBJS-y)
 O_TO_A_STR = $(subst ','\'',$(O_TO_A)) #'# fix syntax highlight
 O_TO_A_DISP = $(if $(V),"$(O_TO_A_STR)","  AR $(@)")

I'm also sure somebody more familiar with gmake could improve it, but it
seems to work quite fine here. I'll wait a bit to see if there are other
suggestions before sending it as a proper patch.

        - Panu -

I did test the patch with minor diff in rte.vars.mk [1], otherwise all
libraries kept needed in final library.

Patch itself looks good, overlinking problem in final binary seems fixed
[2] [3].

But this cause a compilation error for cmdline_test [4]. This is because
of cyclic dependency between librte_eal <-> librte_mempool.

Other applications don't have this compilation error because they use
librte_mempool, and since it is linked against application,  this error
not observed. cmdline_test itself doesn't have any direct call to
librte_mempool.

It is possible to add workaround to cmdline_test [5], (introduce
overlinking back), but should we attack on cyclic dependency instead?


Thanks,
ferruh

---

[1]

diff --git a/mk/exec-env/linuxapp/rte.vars.mk

b/mk/exec-env/linuxapp/rte.vars.mk
index d51bd17..10d37d5 100644

--- a/mk/exec-env/linuxapp/rte.vars.mk
+++ b/mk/exec-env/linuxapp/rte.vars.mk

@@ -46,7 +46,7 @@ EXECENV_CFLAGS  = -pthread
 endif

 # Workaround lack of DT_NEEDED entry
-EXECENV_LDFLAGS = --no-as-needed
+EXECENV_LDFLAGS = --as-needed

 EXECENV_LDLIBS  =
 EXECENV_ASFLAGS =

[2]
# ldd build/app/testpmd
        linux-vdso.so.1 (0x00007ffcff92e000)
        librte_mbuf.so.2.1 => .../build/lib/librte_mbuf.so.2.1
        libethdev.so.4.1 => .../build/lib/libethdev.so.4.1
        librte_mempool.so.2.1 => .../build/lib/librte_mempool.so.2.1
        librte_ring.so.1.1 => .../build/lib/librte_ring.so.1.1
        librte_eal.so.2.1 => .../build/lib/librte_eal.so.2.1
        librte_cmdline.so.2.1 => .../build/lib/librte_cmdline.so.2.1
        librte_pmd_bond.so.1.1 => .../build/lib/librte_pmd_bond.so.1.1
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f6879ff1000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f6879c30000)
        /lib64/ld-linux-x86-64.so.2 (0x0000564998dbd000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f6879a2c000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f6879814000)
        librt.so.1 => /lib64/librt.so.1 (0x00007f687960c000)
        librte_kvargs.so.1.1 => .../build/lib/librte_kvargs.so.1.1

[3]
# ldd -u -r build/app/testpmd
#


[4]
== Build app/cmdline_test
  CC cmdline_test.o
  CC commands.o
  LD cmdline_test
.../build/lib/librte_eal.so: undefined reference to `rte_mempool_lookup'
.../build/lib/librte_eal.so: undefined reference to `rte_mempool_create'
collect2: error: ld returned 1 exit status
.../mk/rte.app.mk:243: recipe for target 'cmdline_test' failed
make[3]: *** [cmdline_test] Error 1


[5]

diff --git a/app/cmdline_test/Makefile b/app/cmdline_test/Makefile
index c6169f5..69ebfb2 100644
--- a/app/cmdline_test/Makefile
+++ b/app/cmdline_test/Makefile

@@ -46,6 +46,7 @@ SRCS-y += commands.c

 CFLAGS += -O3
 CFLAGS += $(WERROR_FLAGS)
+LDFLAGS += --no-as-needed

 # this application needs libraries first
 DEPDIRS-y += lib drivers