Ethercat HAL driver

rwistort
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7 years 9 months ago #124306 by rwistort

Replied by rwistort on topic Ethercat HAL driver

Hello.
I have the same problem as Nico.
When it gets to

Code:

loadrt lcec

it gives

Code:

lcec: dlopen: /home/reid/linuxcnc-dev/rtlib/lcec.so: undefined symbol: ecrt_slave_config_sdo

It seems to need the functions defined in libethercat.so, but the reference is somehow missing.
What do I have to do to account for libethercat.so references when lcec runs?

It seems like there ought to be a -lethercat in the CFLAGS of the RT part of the linuxcnc-ethercat build, but I could not get it to work.

My system is
Linux charles1 4.1.42-rt50 #1 SMP PREEMPT RT Fri Aug 18 00:40:02 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux
ec_debianize-master made itself normally.
Master is up and running after a boot, and ethercat command line works fine.
linuxcnc-ethercat seemed to make fine.
linuxcnc-dev is a fork of 2.8

Tantalizingly close is a tough place to be!

Reid

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rwistort
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7 years 9 months ago #124307 by rwistort

Replied by rwistort on topic Ethercat HAL driver

Forgot to mention that ldd shows that lcec hal module references only a bare-bones set of libs, and libethercat is not among them.

Code:

~/linuxcnc-ethercat/src> ldd lcec.so
	linux-vdso.so.1 =>  (0x00007ffe57b91000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fdba3114000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fdba2d4a000)
	/lib64/ld-linux-x86-64.so.2 (0x0000559916b70000)

Hoping that helped...
Reid

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rwistort
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7 years 9 months ago #124494 by rwistort

Replied by rwistort on topic Ethercat HAL driver

No ideas, hmmm?
I'll give you a hint.

I've attached the verbose output of a clean make of linuxcnc-ethernet. It is way too much information, but it shows that it's a uspace build, and the last line is:

Code:

gcc -shared -Bsymbolic -Wl,-rpath,/home/reid/linuxcnc-dev/lib -L/home/reid/linuxcnc-dev/lib -llinuxcnchal -lethercat -Wl,--version-script,lcec.ver -o lcec.so lcec_main.o lcec_class_enc.o lcec_generic.o lcec_ax5200.o lcec_el1xxx.o lcec_el1252.o lcec_el2521.o lcec_el2xxx.o lcec_el2202.o lcec_el31x2.o lcec_el3255.o lcec_el40x1.o lcec_el40x2.o lcec_el41x2.o lcec_el41x4.o lcec_el5101.o lcec_el5151.o lcec_el5152.o lcec_el6900.o lcec_el1904.o lcec_el2904.o lcec_el7041_1000.o lcec_el7211.o lcec_el7342.o lcec_el95xx.o lcec_em7004.o lcec_stmds5k.o lcec_deasda.o -lm

Or, to simplify:

Code:

gcc -shared -o lcec.so -lethercat -L/home/reid/linuxcnc-dev/lib ...etc...

Yes, libethercat.so exists in /home/reid/linuxcnc-dev/lib, and

Code:

~/linuxcnc-ethercat/src> nm -D lcec.so
                 w __cxa_finalize
                 U ecrt_domain_data
                 U ecrt_domain_process
                 U ecrt_domain_queue
                 U ecrt_domain_reg_pdo_entry_list
                 U ecrt_domain_size
                 U ecrt_master_activate
                 U ecrt_master_application_time
                 U ecrt_master_create_domain
                 U ecrt_master_deactivate
                 U ecrt_master_read_idn
                 U ecrt_master_receive
                 U ecrt_master_sdo_upload
                 U ecrt_master_send
                 U ecrt_master_slave_config
                 U ecrt_master_state
                 U ecrt_master_sync_reference_clock
                 U ecrt_master_sync_slave_clocks
                 U ecrt_release_master
                 U ecrt_request_master
                 U ecrt_slave_config_complete_sdo
                 U ecrt_slave_config_dc
                 U ecrt_slave_config_idn
                 U ecrt_slave_config_pdos
                 U ecrt_slave_config_sdo
                 U ecrt_slave_config_sdo8
                 U ecrt_slave_config_state
                 U ecrt_slave_config_watchdog
                 U free
                 U gettimeofday
                 w __gmon_start__
                 U hal_exit
                 U hal_export_funct
                 U hal_init
                 U hal_malloc
                 U hal_param_new
                 U hal_pin_new
                 U hal_ready
                 w _ITM_deregisterTMCloneTable
                 w _ITM_registerTMCloneTable
                 w _Jv_RegisterClasses
                 U malloc
                 U pow
00000000000053cc T rtapi_app_exit
00000000000065a2 T rtapi_app_main
                 U rtapi_get_time
000000000021a6a0 D rtapi_info_author
000000000021a698 D rtapi_info_description
000000000021a6a8 D rtapi_info_license
                 U rtapi_mutex_get
                 U rtapi_mutex_give
                 U rtapi_print_msg
                 U rtapi_shmem_delete
                 U rtapi_shmem_getptr
                 U rtapi_shmem_new
                 U rtapi_snprintf
                 U rtapi_vsnprintf
                 U __stack_chk_fail
                 U strncpy
~/linuxcnc-ethercat/src> 

Which confirms that the ecrt_* symbols from libethercat did not get folded into lcec.so.

I'm doing something stupid. How do I get these symbols to resolve when hal gets to loadrt lcec?

Thanks,
Reid

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shameless
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7 years 9 months ago #124550 by shameless

Replied by shameless on topic Ethercat HAL driver

@rwistort, I replace the src/realtime.mk with the realtime.mk in the 0.9.1 version which is found on the GitHub. It works, you can see libethercat when you ldd lcec.so. But there are other problems.
Regards!

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Grotius
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7 years 9 months ago #124611 by Grotius

Replied by Grotius on topic Ethercat HAL driver

@Reid,

linuxcnc-dev is a fork of 2.8

I was thinking. Did you copy lcec.conf to your linuxcnc-dev bin directory?

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rwistort
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Junior Member

7 years 9 months ago #124625 by rwistort

Replied by rwistort on topic Ethercat HAL driver

@Grotius
I use symbolic links in /bin and /rtlib so the binaries are always up to date. lcec_conf loads OK and its 2 pins show up in hal.

@shameless
I copied (just the) realtime.mk file from 0.9.1, and it cleared up the "undefined symbol: ecrt_slave_config_sdo" problem. Thanks!

It went on to complain about "undefined symbol: rtapi_mutex_get". This problem has shown up in this forum (see Rene 6/6/18, Nico 10/24/18, Nico 10/28/18, Hawkeye 1/10/19 step 6). So I added #include rtapi_mutex.h in lcec_main.c and changed permissions to /dev/EtherCAT0, and now both lcec_conf and lcec load, and hal is full of lcec pins to play with.
Woo hoo!

Sadly, my (one and only) servo drive exploded in a flash of sparks and smoke the other day, and I can't play with my new pins until I get it back from warranty repair. SAD!!

I am one of those people who wonders what make is really doing under all those covers, so I tried to figure out what, in the 0.9.1 config.mk, makes the difference.
When it gets right down to issuing a gcc command, the 091 and the latest gcc command for .c -> .o differs by:

Code:

common: gcc -o lcec_em7004.o -Os -g -I. -I/home/reid/linuxcnc-dev/src/include -DUSPACE -fno-fast-math -mieee-fp -fno-unsafe-math-optimizations -DRTAPI -D_GNU_SOURCE -Drealtime -D__MODULE__ -I/home/reid/linuxcnc-dev/include -DSIM -fPIC -c lcec_em7004.c
091   : -Os
new   : -Wframe-larger-than=2560

I doubt that this is part of the problem.

The command line for the link step .o -> .so differs by:

Code:

common: gcc -shared -o lcec.so -Wl,-rpath,/home/reid/linuxcnc-dev/lib -L/home/reid/linuxcnc-dev/lib -llinuxcnchal -lethercat [object-name-list]
091   : -lrt
new   : -lm  -Bsymbolic -Wl,--version-script,lcec.ver

I could not figure out where, in all of make's mechanics, the "-Bsymbolic -Wl,--version-script,lcec.ver" comes from.
Their presence, though, seems to cause a 2-step link which I am totally unfamiliar with. Something like:

Code:

ld -d -r -o lcec.tmp [obj-list]
objcopy -j .rtapi_export -O binary lcec.tmp lcec.sym
(echo '{ global : '; tr -s '\0' < lcec.sym | xargs -r0 printf '%s;\n' | grep .; echo 'local : * ; };') > lcec.ver
gcc -shared -Bsymbolic -Wl,-rpath,/home/reid/linuxcnc-dev/lib -L/home/reid/linuxcnc-dev/lib -llinuxcnchal -lethercat -lm -Wl,--version-script,lcec.ver -o lcec.so [obj-list]

Can anybody out there give us a bird's eye view of what make is trying to do here?

Admit it! We're all a little bit confused and a little bit curious!

Thanks
Reid

The following user(s) said Thank You: Nico2017

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