Frequently Asked Questions¶
I’ve opened hs38.tcf and GCC options include -mcpu=hs34. Why hs34 instead of hs38?¶
Possible values of -mcpu= options are orthogonal to names of IPlib templates and respective TCF.
GCC option -mcpu= supports both hs34 and hs38 values, but they are different - hs38 enables
more features, like -mll64 which are not present in hs34. ARC HS IPlib template hs38 doesn’t
contain double-word load/store, therefore -mcpu=hs38 is not compatible with this template.
-mcpu=hs34, however, is compatible and that is why TCF generator uses this value. Refer
Target Options sections for a full list of possible -mcpu
values and what IPlibrary templates they correspond to.
There are can’t resolve symbol error messages when using gdbserver on Linux for ARC targets¶
This error message might appear when gdbserver is a statically linked application. Even though it
is linked statically, gdbserver still opens libthread_db.so library using dlopen() function.
There is a circular dependency here, as libthread_db.so expects several dynamic symbols to be already defined in the loading application (gdbserver in this case). However statically linked gdbserver does not export those dynamic symbols,
therefore dlopen() invocation causes those error messages. In practice there have not been noticed any downside of
this, even when debugging applications with threads, however that was tried only with simple test cases. To fix
this issue, either rebuild gdbserver as a dynamically linked application, or pass option
--with-libthread-db=-lthread_db to configure script of script. In this case gdbserver will link
with libthread_db statically, instead of opening it with dlopen() and dependency on symbols will
be resolved at link time.
GDB prints an error message that XML support has been disabled at compile time¶
GDB uses Expat library to parse XML files. Support of XML files is optional for GDB, therefore it can be built without Expat available, however for ARC it usually required to have support of XML to read target description files. Mentioned error message might happen if GDB has been built without available development files for the Expat. On Linux systems those should be available as package in package manager.
How to reset ARC SDP board programmatically (without pressing Reset button)?¶
It is possible to reset ARC SDP board without touching the physical button on the board. This can be done using the special OpenOCD script:
Note that OpenOCD will crash with a segmentation fault after executing this script - this is expected
and happens only after board has been reset, but that means that other OpenOCD scripts cannot be used
in chain with reset_sdp.tcl, first OpenOCD should be invoked to reset the board, second it should be
invoked to run as an actual debugger.
Can I program FPGA's in ARC EM Starter Kit or in ARC SDP?¶
OpenOCD has some support for programming of FPGA’s over JTAG, however it is not officially supported for ARC development systems.
When debugging ARC EM core in AXS101 with Ashling Opella-XD and GDBserver I get an error messages and GDB shows that all memory and registers are zeroes¶
Decrease a JTAG frequency to no more than 5MHz using an Ashling GDBserver option --jtag-frequency.
This particular problem can be noted if GDBserver prints:
Error: Core is running (unexpected), attempting to halt...
Error: Core is running (unexpected), attempting to halt...
Error: Unable to halt core
While GDB shows that whole memory is just zeroes and all register values are also zeroes.