Re: gcj static crosscompiling raises issues with boehm-gc

[David Daney <ddaney@caviumnetworks.com>]

On 10/06/2010 09:53 AM, Andreas Frisch wrote:
> Am Mittwoch, 6. Oktober 2010, um 08:51:40 schrieb David Daney:
>> On 10/06/2010 07:25 AM, Andrew Haley wrote:
>>> On 10/06/2010 09:43 AM, Andreas Frisch wrote:
>>>> hi gcj experts,
>>>>
>>>> i've spent some time already trying to statically cross compile a java
>>>> source for an embedded mipsel architecture. i'm using openembedded
>>>> and gcc-4.4.4 with the latest java part imported from master
>>>>
>>>> in the makefile, i am using the command
>>>>
>>>> $(CROSS_COMPILE)gcj $(JFLAGS) $(SOURCES) \
>>>>
>>>> 		-static-libgcj \
>>>> 		-fjni \
>>>> 		-g \
>>>> 		-o dumphd-mipsel-static \
>>>> 		
>>>> 		 --main=dumphd.core.DumpHD \
>>>> 		
>>>> 		-nostdlib \
>>>> 		-L/dream/oe1.6/dm8000/build/tmp/staging/mipsel-oe-linux/usr/lib
> \
>>>> 		-L/dream/projects/bluray/aacskeys-0.4.0c-mipsel/lib/linux/ \
>>>> 		-Wl,-rpath-link,/dream/oe1.6/dm8000/build/tmp/staging/mipsel-oe-
>>>>
>>>> linux/usr/lib \
>>>>
>>>> 		-Wl,-rpath-link,/dream/projects/bluray/aacskeys-0.4.0c-
>>>>
>>>> mipsel/lib/linux/ -laacskeys \
>>>>
>>>> 		-shared-libgcc -Wl,-non_shared -lgcj -Wl,-call_shared -lstdc++ -
>>>>
>>>> Wl,--as-needed -lgcc_s -lpthread -lc -lm -ldl -lrt -Wl,--no-as-needed
>>>> -Wl,-O1
>>>>
>>>> this may contain a lot of redundancies or look silly in many ways but
>>>> for right now i just aggregated as much as possible in there from
>>>> what i could find online.
>>>>
>>>> i've also set
>>>> CLASSPATH=/dream/oe1.6/dm8000/build/tmp/cross/mipsel/bin/ecj.jar:./
>>>>
>>>> when i run make, linking fails:
>>>>
>>>> /dream/oe1.6/dm8000/build/tmp/cross/mipsel/lib/gcc/mipsel-oe-
>>>> linux/4.4.4/../../../../mipsel-oe-linux/bin/ld: warning: cannot find
>>>> entry symbol __start; defaulting to 00000000004084b0
>>>> /dream/oe1.6/dm8000/build/tmp/cross/mipsel/lib/gcc/mipsel-oe-
>>>> linux/4.4.4/../../../../mipsel-oe-linux/lib/libgcj.a(dyn_load.o): In
>>>> function `GC_register_dynamic_libraries_dl_iterate_phdr':
>>>> /dream/oe1.6/dm8000/build/tmp/work/mipsel-oe-linux/gcc-cross-4.4.4-
>>>> r0.1/gcc-4.4.4/boehm-gc/dyn_load.c:454: undefined reference to
>>>> `__data_start'
>>>> /dream/oe1.6/dm8000/build/tmp/cross/mipsel/lib/gcc/mipsel-oe-
>>>> linux/4.4.4/../../../../mipsel-oe-linux/lib/libgcj.a(os_dep.o): In
>>>> function `GC_register_data_segments':
>>>> /dream/oe1.6/dm8000/build/tmp/work/mipsel-oe-linux/gcc-cross-4.4.4-
>>>> r0.1/gcc-4.4.4/boehm-gc/os_dep.c:1450: undefined reference to
>>>> `__data_start' collect2: ld returned 1 exit status
>>>> make: *** [dumphd-static-new] Error 1
>>>>
>>>> i'd be grateful for any suggestions or hints.
>>>
>>> This looks completely broken: it seems to be trying to statically link
>>> against libgcj.  Try it without -non_shared.
>>
>> To expound on this, the '-static-libgcj' option was created so that all
>> the other things you have there would be unneeded.
>>
>> I doubt you want any of: -shared-libgcc -Wl,-non_shared -lgcj
>> -Wl,-call_shared -lstdc++ -Wl,--as-needed -lgcc_s -lpthread -lc -lm -ldl
>> -lrt -Wl,--no-as-needed -Wl,-O1
>>
>>
>> Start off with -static-libgcj on a very simple 'hello-world' type
>> program.  Then start adding all your other things in.
>>
>> David Daney
>
> hi david!
>
> actually i was already successful statically cross compiling java programs as
> complex as projectx:
>
> it works both the traditional way
> projectx-static-oldfashioned: $(OBJS)
> 	$(CROSS_COMPILE)gcj $(JFLAGS) -c -o ac3.o --resource ac3.bin
> ../resources/ac3.bin
> 	$(CROSS_COMPILE)gcj $(JFLAGS) -c -o pjxresources_en.o --resource
> pjxresources_en.properties ../resources/pjxresources_en.properties
> 	$(CROSS_COMPILE)gcj $(JFLAGS) $(OBJS) pjxresources_en.o ac3.o -
> Djava.awt.headless=true --main=net.sourceforge.dvb.projectx.common.Start -
> save-temps
> 	$(CROSS_COMPILE)gcc -o projectx $(OBJS) pjxresources_en.o ac3.o
> ./net.sourceforge.dvb.projectx.common.Startmain.i \
> 	-shared-libgcc -Wl,-non_shared -lgcj -Wl,-call_shared -lsupc++ -Wl,--as-
> needed -lgcc_s -lpthread -lc -lm -ldl -lrt -Wl,--no-as-needed
> 	$(CROSS_COMPILE)strip --strip-all projectx
>
> and with the new nifty -static-libgcj convenience parameter
> projectx-static:
> 	$(CROSS_COMPILE)gcj $(JFLAGS) -c -o ac3.o --resource ac3.bin
> ../resources/ac3.bin
> 	$(CROSS_COMPILE)gcj $(JFLAGS) -c -o pjxresources_en.o --resource
> pjxresources_en.properties ../resources/pjxresources_en.properties
> 	$(CROSS_COMPILE)gcj -static-libgcj -o projectx $(SOURCES)
> pjxresources_en.o ac3.o \
> 	-Djava.awt.headless=true --main=net.sourceforge.dvb.projectx.common.Start
> 	$(CROSS_COMPILE)strip --strip-all projectx
>
> however, what's different about this new program is that it requires that c++
> compiled shared object libaacskeys.so and that's what causes my problems i
> guess
>

Things can get complicated when linking in C++ code with the gcj driver 
program.  I would think all you would need is -lsupc++, and perhaps 
-lstdc++.

-nostdlib looks a bit questionable to me.

In any event it is good to see that people are still making use of gcj 
on mips.

David Daney