Re: [Gems-users] Segmentation Fault

[Dan Gibson <degibson@xxxxxxxx>]

Add the following to your script, right after dstc-disable:

magic-break-enable

Regards,
Dan

PS:
We also load ruby in the middle of execution...but we don't install 
python hap callbacks (for simplicity). Our scripts look something like this:
read-configuration [config]
cpu-switch-time 1
c 1000
instruction-fetch-mode instruction-fetch-trace
istc-disable
dstc-disable
magic-break-enable
c # Eventually, we hit our magic breakpoint
load-module ruby
ruby0.setparam...
ruby0.init
c # Eventually, we hit another magic breakpoint (the one to stop the sim)
ruby0.dump-stats
q


Marco Tirado wrote:
> Hello Dan:
>  
> Thank you for answering so quickly. We are not getting the 
> segmentation error now, the problem was that we were loading the ruby 
> module but we did not initialize it with instruction ruby0.init untill 
> we went into a MAGIC_BREAKPOINT subroutine that we have impemented in 
> our code. However we still have some problems trying to load ruby on a 
> magic breakpoint subroutine. We are running SPLASH2 on a sarek SPARC 
> target and we want to start ruby in a specific part of the workload 
> code so we are using magic breakpoints. Our script is the following:
>  
>
> read-configuration /localdisk/cmp/chkpt/cold_watersp4p.chkpt
>
> instruction-fetch-mode instruction-fetch-trace
> istc-disable
> dstc-disable
>
> $control = 0
> @def hap_callback(user_arg, cpu, arg):          
>  if simenv.control == 0:
>     eval_cli_line("run-command-file startRuby.simics")
>  else:
>            eval_cli_line("run-command-file stopRuby.simics")
>  simenv.control = simenv.control+1
> @SIM_hap_add_callback("Core_Magic_Instruction", hap_callback, None)
> echo("Magic interruption handler conf sucess")
> c
> We added the MAGIC_BREAKPOINT instruction in the workload source right 
> before the important part of the code starts, and we start ruby there, 
> the script looks lile this:
>  
> load-module ruby
> ruby0.setparam g_NUM_PROCESSORS 4
> ruby0.setparam g_NUM_L2_BANKS 4
> ruby0.setparam g_NUM_MEMORIES 4
> ruby0.setparam g_PROCS_PER_CHIP 4
> ruby0.setparam g_endpoint_bandwidth 1000
> ruby0.setparam_str g_NETWORK_TOPOLOGY FILE_SPECIFIED
> ruby0.setparam_str g_CACHE_DESIGN NUCA_Mesh
> ruby0.setparam L1_CACHE_NUM_SETS_BITS 8
> #ruby0.setparam DIR_CACHE_NUM_SETS_BITS 8
> ruby0.setparam L2_CACHE_NUM_SETS_BITS 12
> ruby0.setparam g_DATA_BLOCK_BYTES 32
> ruby0.setparam g_MEMORY_SIZE_BYTES 4294967296
>
> ruby0.init
>  
>
> However we get an error message once we go into the MAGIC_BREAKPOINT 
> subroutine since we need to stop simics in order to load ruby. The 
> message is:
>  
> [start2.simics:37] c
> [startRuby.simics:1] load-module ruby
> This command cannot be used when Simics is running.
> [startRuby.simics:1] the command did not complete properly; 
> interrupting script
>  
> We thought the magic breakpoint would stop simics, but it is not the 
> case. Are we missing something? is there another way to do this? 
> Thanks again. Best Regards
>  
> Enric and Marco
>
>  
> On 5/15/06, *Dan Gibson* <degibson@xxxxxxxx 
> <mailto:degibson@xxxxxxxx>> wrote:
>     Marco+Enric,
>
>     As you may have guessed from previous posts on this topic, Ruby will
>     segfault if it is loaded before a "phys_mem0" object exists (the
>     call to
>     acquire this object returns NULL, and the pointer is then used).
>     However, it looks like you are successfully loading a checkpoint
>     before
>     installing ruby. Can you confirm that "phys_mem0" exists before
>     load-module ruby?
>
>     Have a look in Ruby's module/ruby.c file, in the init_local()
>     function.
>     Try inserting some print statements to determine if this function
>     returns successfully. If not, the segfault is certainly somewhere
>     within
>     this function (only this function is executed at load-time).
>
>     Regards,
>     Dan
>
>     Enric Herrero wrote:
>     > Hi,
>     > We are having a similar problem as the one that had
>     > Arrvindh this march. Sudenly when we try to load Ruby
>     > we get a segmentation fault like that:
>     >
>     > simics> run-command-file ../sarek/start.simics
>     > Turning I-STC off and flushing old data
>     > Turning D-STC off and flushing old data
>     > successful installation of the ruby timing model.
>     > ***  Simics getting shaky, switching to 'safe' mode.
>     > Simics (main thread) received a segmentation fault.
>     > Will try to recuperate.
>     > simics>
>     >
>     > And the script we run is the following:
>     >
>     > read-configuration
>     > /localdisk/cmp/chkpt/cold_watersp4p.chkpt
>     > instruction-fetch-mode instruction-fetch-trace
>     > istc-disable
>     > dstc-disable
>     > load-module ruby
>     > ruby0.setparam g_NUM_PROCESSORS 4
>     > ruby0.setparam g_NUM_L2_BANKS 4
>     > ruby0.setparam g_NUM_MEMORIES 4
>     > ruby0.setparam g_PROCS_PER_CHIP 4
>     > ruby0.setparam L1_CACHE_NUM_SETS_BITS 8
>     > ruby0.setparam L2_CACHE_NUM_SETS_BITS 12
>     > ruby0.setparam g_DATA_BLOCK_BYTES 32
>     > ruby0.setparam g_MEMORY_SIZE_BYTES 4294967296 (32
>     > bits)
>     > c
>     >
>     > The original configuration with the simics script is
>     > the following:
>     >
>     > # set up 4 processors with 512MB
>     > @boards = {0 : [[0, 4, 2048]]}
>     > @sarek_disk_size = 4256972800L
>     > @sarek_files = [["sarek-sol9-install.disk", "ro", 0,
>     > 4256972800L]]
>     >
>     > Also if we check the memory in simics it appears like
>     > that:
>     >
>     > simics> phys_mem0.map
>     > base               object     fn offs   length
>     >
>     > 0x0000000000000000 memory0    0 0x0     0x80000000
>     > 0x000007fff07ffff0 hfs0       0 0x0     0x10
>     > simics>
>     >
>     > Does anyone know how to solve this problem?
>     > Thank you very much
>     >
>     > /Marco and Enric
>     >
>     >
>     >
>     >
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