Investigating a segfault in my code, looking for GetBuiltinsCount in the V8 source code leads me to this comment:
/**
* NativesStore stores the 'native' (builtin) JS libraries.
*
* NativesStore needs to be initialized before using V8, usually by the
* embedder calling v8::SetNativesDataBlob, which calls SetNativesFromFile
* below.
*/
How am I, the embedder supposed to use v8::SetNativesDataBlob?
The d8 interpreter does call this method, but it's not at all clear what it's doing and why.
The basic samples do not call this method.
A bit over a year later, I find myself back at this question, and now I know the answer.
You can compile V8 with external startup data ("snapshot") or without.
If you compiled with snapshot data, call V8::InitializeExternalStartupData as shown in the Hello World example code. You don't call v8::SetNativesDataBlob directly.
Otherwise, the solution is to compile without snapshot data. Then, you don't need to call either of the aforementioned functions at all. Here's one answer on how to configure this in your build process. Note, using snapshot data decreases process start-up time.
Related
I've been having an issue with a certain function call in the
dphaseWeighted = af::convolve(dphaseWeighted, m_slowTimeFilter);
which seem to produce nothing but nan's.
The back ground is we have recently switched from using AF OpenCL to AF Cuda and the problem that we are seeing happens in the function.
dphaseWeighted = af::convolve(dphaseWeighted, m_slowTimeFilter);
This seems to work well when using OpenCL.
Unfortunatley, I can't give you the whole function because of IP. only a couple of snippets.
This convolve lies deep with in a phase extract piece of code. and is actualy the second part of that code which uses the af::convolve funtion.
The first function seems to behave as expected, with sensible floating point data out.
but then when it comes to the second function all I'm seeing is nan's coming out ( I view that with af_print amd dumping the data to a file.
in the CMakeList I include
include_directories(${ArrayFire_INCLUDE_DIRS})
and
target_link_libraries(DASPhaseInternalLib ${ArrayFire_CUDA_LIBRARIES})
and it builds as expected.
Has anyone experience any think like this before?
The Point Cloud library comes with an executable pcl_hdl_viewer_simple that I can run (./pcl_hdl_viewer_simple) without any extra arguments to get live data from a Velodyne LIDAR HDL32.
The source code for this program is supposed to be hdl_viewer_simple.cpp. A simplified version of the code is given on this page which cannot be compiled readily and requires a tiny bit of tweaking to make it compile.
My problem is that the executable that I build myself for both the versions are not able to run. I always get the smart pointer error "Assertion px!=0" error. I am not sure if I am not executing the program in the correct way or what. The executable is supposed to be executed like
./hdl_viewer_simple -calibrationFile hdl32calib.xml -pcapFile file.pcap
in case of playing from previously recorded PCAP files or just ./hdl_viewer_simple if wanting to get live data from the real sensor. However, I always get the assertion failed error.
Has anyone been able to run the executables? I do not want to use the ROS drivers
"Assertion px!=0" is occurring because your pointer is not initialized.
Now that being said, you could initialize it inside your routines, in case the pointer is NULL, especially for data input.
in here, you can try updating the line 83 like this :
CloudConstPtr cloud(new Cloud); //initializing your pointer
and hopefully, it will work.
Cheers,
Here is the part of call stack returned by kd command. I want to know what parameters were passed to myutil!myclass::somefunc. How do I get those parameters using windbg?
0a11f614 0a11f634
0a11f618 7686592c rpcrt4!Invoke+0x2a
0a11f61c 0e7b2c98
0a11f620 03edad48
0a11f624 03edaba8
0a11f628 00000206
0a11f62c 00000003
0a11f630 0a11f820
0a11f634 0a11fa38
0a11f638 768e05f1 rpcrt4!NdrStubCall2+0x2ea
0a11f63c 6dbc12b2*** WARNING: Unable to verify timestamp for myutil
myutil!myclass::somefunc
Thanks in advance,
-Neel.
about the stack being different
There is no reason that the stack shown by kd and kp would be different. They are essentially different representation on the same data.
If you paste the stack here may be we will be point out whats going on!
Are you sure you running both commands in the same place ?
how to check if symbols are loaded correctly
execute the command : "lml" to see for which binaries, symbols have been loaded.
Coming to your original question
kP is the simplest way to see the parameters that are being passed to the function.
another way to do the same thing is
a. run "kn" so that you see frame numbers in the stack trace.
b. move to the frame of interest by doing ".frame
c. now dump the variables using "dv"
If you are really passionte you can read about paramter passing. Then all you would need is the EBP + some assembly code reading to figure out which parameters we passed.
I started to mess with Ypsilon, which is a C++ implementation of Scheme.
It conforms R6RS, features fast garbage collector, supports multi-core CPUs and Unicode but has a LACK of documentation, C++ code examples and comments in the code!
Authors provide it as a standalone console application.
My goal is to use it as a scripting engine in an image processing application.
The source code is well structured, but the structure is unfamiliar.
I spent two weeks penetrating it, and here's what I've found out:
All communication with outer world is done via C++ structures called
ports, they correspond to Scheme ports.
Virtual machine has 3 ports: IN, OUT and ERROR.
Ports can be std-ports (via console), socket-ports,
bytevector-ports, named-file-ports and custom-ports.
Each custom port must provide a filled structure called handlers.
Handlers is a vector containing 6 elements: 1st one is a boolean
(whether
port is textual), and other five are function pointers (onRead, onWrite, onSetPos, onGetPos, onClose).
As far as I understand, I need to implement 3 custom ports (IN, OUT and ERROR).
But for now I can't figure out, what are the input parameters of each function (onRead, onWrite, onSetPos, onGetPos, onClose) in handlers.
Unfortunately, there is neither example of implementing a custom port no example of following stuff:
C++ to Scheme function bindings (provided examples are a bunch of
.scm-files, still unclear what to do on the C++ side).
Compiling and
running bytecode (via bytevector-ports? But how to compile text to
bytecode?).
Summarizing, if anyone provides a C++ example of any scenario mentioned above, it would significantly save my time.
Thanks in advance!
Okay, from what I can read of the source code, here's how the various handlers get called (this is all unofficial, based purely on source code inspection):
Read handler: (lambda (bv off len)): takes a bytevector (which your handler will put the read data into), an offset (fixnum), and a length (fixnum). You should read in up to len bytes, placing those bytes into bv starting at off. Return the number of bytes actually read in (as a fixnum).
Write handler: (lambda (bv off len)): takes a bytevector (which contains the data to write), an offset (fixnum), and a length (fixnum). Grab up to len bytes from bv, starting at off, and write them out. Return the number of bytes actually written (as a fixnum).
Get position handler: (lambda (pos)) (called in text mode only): Allows you to store some data for pos so that a future call to the set position handler with the same pos value will reset the position back to the current position. Return value ignored.
Set position handler: (lambda (pos)): Move the current position to the value of pos. Return value ignored.
Close handler: (lambda ()): Close the port. Return value ignored.
To answer another question you had, about compiling and running "bytecode":
To compile an expression, use compile. This returns a code object.
There is no publicly-exported approach to run this code object. Internally, the code uses run-vmi, but you can't access this from outside code.
Internally, the only place where compiled code is loaded and used is in its auto-compile-cache system.
Have a look at heap/boot/eval.scm for details. (Again, this is not an official response, but based purely on personal experimentation and source code inspection.)
I am trying to print out the stack in different routines using a pin tool. I am able to get all of the routines but I am a little confused on how to get the addresses stored in the registers in the stack of that routine.
What I have is this:
VOID SETRTN_CONTEXT(CONTEXT * ctxt)
{
ADDRINT reg_address;
PIN_SaveContext(ctxt, &m_ctxt);
reg_address = PIN_GetContextReg(&m_ctxt, REG_STACK_PTR);
}
and in another function I have this piece of code that calls that function:
for(rtn = SEC_RtnHead(sec); RTN_Valid(rtn); rtn = RTN_Next(rtn) )
{
RTN_Open(rtn);
RTN_InsertCall(rtn, IPOINT_BEFORE, (AFUNPTR)SETRTN_CONTEXT,
IARG_CONST_CONTEXT, IARG_THREAD_ID, IARG_END);
RTN_Close(rtn);
}
I am a little confused on when the routine calls that function since I am only getting one result and I get it after attaching with Pin and waiting a couple of seconds.
Any pinheads that might help me on this one? I understand that I need the context from a routine in order to get the registers but I cannot find any function that returns the context as an object...
In your RTN_InsertCall, you add the thread id, and in your SETRTN_CONTEXT function declaration you don't receive the thread id... might want to fix that.
Also, in your analysis routine SETRTN_CONTEXT, you're not actually saving anything external to the application. I could be wrong if m_ctxt is a global variable that you're manipulating elsewhere, which how could that be sound unless you did that for every time the analysis routine ran and in a thread safe way?
Clearly, you want to write the information to some file or output. I recommend using some kind of xml tool; this makes it easy to parse, and if you write your pintools smartly, you can exchange the format of the output by obeying some interface contract.
Also to clarify your confusion, you try to insert the analysis routine to run before every single function in a particular image; every time that function is called in that image, your SETRTN_CONTEXT runs.