Adding an external static library to Trusted Application

[haleyyew]

Hi, I am trying to put the protobuf-c.a library into my Trusted Application. I tried this hackish way where I combined my static library with libutils.a. I also tried to add the static library independently by specifying it in ldargs-$(binary). However for both methods I got the following error:

/home/haoran/devel/optee/optee_app/../toolchains/aarch32/bin/arm-linux-gnueabihf-ld: /home/haoran/devel/optee/optee_os/out/arm/export-ta_arm32/lib/libutils.a(protobuf-c.o): relocation R_ARM_THM_MOVW_ABS_NC against `a local symbol' can not be used when making a shared object; recompile with -fPIC
/home/haoran/devel/optee/optee_os/out/arm/export-ta_arm32/lib/libutils.a: error adding symbols: Bad value

I was wondering, if you can give me any pointers on how the static library for protobuf-c.a should be compiled or added to the build Makefile so the build for the TA works?

My make file currently looks like this:

CFG_TEE_TA_LOG_LEVEL = 2
CPPFLAGS += -DCFG_TEE_TA_LOG_LEVEL=$(CFG_TEE_TA_LOG_LEVEL) -I../common
#CPPFLAGS += -I/usr/local/include 
CPPFLAGS += -I/home/haoran/devel/optee/toolchains/aarch32/arm-linux-gnueabihf/libc/include

BINARY=ffa39702-9ce0-47e0-a1cb4048cfdb847d

include $(TA_DEV_KIT_DIR)/mk/ta_dev_kit.mk
#ldargs-$(binary).elf += -lprotobuf-c -L/usr/local/lib
#ldargs-$(binary).elf += -lprotobuf-c -L/usr/lib 
#ldargs-$(binary).elf += -lprotobuf-c 
#/home/haoran/devel/optee/toolchains/aarch32/arm-linux-gnueabihf/libc/lib
#ldargs-$(binary).elf += /home/haoran/devel/optee/toolchains/aarch32/arm-linux-gnueabihf/libc/lib/libprotobuf-c.so.1.0.0

[jenswi-linaro]

You'll find the interesting flags in $(TA_DEV_KIT_DIR)/mk/conf.mk

[haleyyew]

Can you be a little more specific on how a static .a library can be linked to the object files after compilation? There are only cflags in $(TA_DEV_KIT_DIR)/mk/conf.mk but I'm looking for ld that can be set to a static library.

Thanks

[peterfeifanchen]

perhaps try in ta_dev_kit.mk:

libdirs += $(ta-dev-kit-dir)/lib
libnames += utils utee mpa utils utee
libdeps += $(ta-dev-kit-dir)/lib/libutils.a
libdeps += $(ta-dev-kit-dir)/lib/libmpa.a
libdeps += $(ta-dev-kit-dir)/lib/libutee.a

Add your static library here and drop the library itself into the $(ta_dev_kit_dir)/lib. If it depends on any library such as libutils.a, make sure you add it before that.

[haleyyew]

After adding libdeps += $(ta-dev-kit-dir)/lib/libprotobuf-c.a in ta_dev_kit.mk, I still get the

relocation R_ARM_THM_MOVW_ABS_NC against `a local symbol' can not be used when making a shared object; recompile with -fPIC

error.
Help is much appreciated.

[jenswi-linaro]

Try to recompile your static library with the compiler flags found in $(TA_DEV_KIT_DIR)/mk/conf.mk, it looks like something is incompatible.

[haleyyew]

I managed to include the external library without having to link it to a TA. Since I already have the source code for the library, I didn't have to use the shared object of the library, I added all of the library's source code as part of the TA instead.