Error using OpenCL API

[muzapparjan]

Here is my code:

cl = CL.GetApi();
uint platformCount;
cl.GetPlatformIDs(0, null, &platformCount);

And it threw exception: System.DivideByZeroException:“Attempted to divide by zero.” while executing GetPlatformIDs(xxx).

Then I tried to write as the script in Silk.Net/src/Lab/CLMultiplication/Program.cs:

cl = CL.GetApi();
IntPtr platform;
cl.GetPlatformIDs(1, &platform, null);

And it threw the same exception.

Environment:

• Windows 10 64bit
• Using Silk.Net.OpenGL & ..OpenCL & ..Windowing & ..Common & ..Input & ..OCL Extention KHR

[Perksey]

Can you please give the complete exception including the stack trace? I can't reproduce here.

[muzapparjan]

System.DivideByZeroException
HResult=0x80020012
Message=Attempted to divide by zero.
Source=<无法计算异常源>
StackTrace:
<无法计算异常堆栈跟踪>

[Perksey]

Oh nevermind I can see what I need to see.

[Perksey]

Can you try updating to Silk.NET 2.0 Preview 5?

[muzapparjan]

Emmmm
I am a green hand...
Can you please tell me how to update?

[muzapparjan]

I downloaded it directly on NuGet

[Perksey]

• Right click on your project, and select Manage NuGet packages
• Head over to the updates tab, and select Include prerelease

Now the updated verisons should pop up. Alternatively if that's giving you issues:

• open the .csproj file in a text editor
• replace every reference of "1.9.0" with "2.0.0-preview5"

[muzapparjan]

Wow really thanks!!!

[muzapparjan]

...
It still throws the same exception

[Perksey]

Can you send me the stack trace again? The $exception.StackTrace string is what clued me in last time. It's impossible that that's the same, if it is you didn't upgrade correctly.

[muzapparjan]

at Silk.NET.OpenCL.CL.GetPlatformIDs(UInt32 num_entries, IntPtr* platforms, UInt32* num_platforms)
at Study.ImageProcessing.Test.Tests.CLTrialTask.OnLoad() in E:\CSharp\Study\Study.ImageProcessing.Test\Tests\CLTrialTask.cs:line 52
at Silk.NET.Windowing.Internals.ViewImplementationBase.Initialize()
at Silk.NET.Windowing.WindowExtensions.Run(IView view)
at Study.ImageProcessing.Test.Tests.CLTrialTask.Run(String[] args, Object[] inputs) in E:\CSharp\Study\Study.ImageProcessing.Test\Tests\CLTrialTask.cs:line 31
at Study.ImageProcessing.Test.Entrance.Main(String[] args) in E:\CSharp\Study\Study.ImageProcessing.Test\Entrance.cs:line 9"

[muzapparjan]

[muzapparjan]

My repository named "Study" is the problem project

[Perksey]

Your repo does not have the images required.

[muzapparjan]

Wow didn't it throw exceptions at calling clGetPlatformIDs API?

[Perksey]

Nope.

[muzapparjan]

I cried

[muzapparjan]

[Perksey]

It's strange because we don't do any division. Can you try right clicking on the call stack window and enabling "Show external code"?

[muzapparjan]

[muzapparjan]

未知 means unknown

[Perksey]

What's the text at the very top of the call stack?

[muzapparjan]

调用堆栈：Call Stack
名称：Name
托管到本机的转换：Transition from managed to host(???)

[Perksey]

This looks to be an OpenCL bug, converting to discussion.

Can you try updating your drivers?

[Perksey]

Also, can you try Enable native code debugging and see if anything changes?

[muzapparjan]

I enabled all native code debugging options in solution and the result is:

[muzapparjan]

帧状态：Frame State
非用户代码，已加载符号：Isn't written by user, symbol is loaded
无可用源：No Available Source

[muzapparjan]

I updated nvidia driver from v457.xx to v460.89 but it still not work

[Perksey]

That's a shame. This unfortunately is a driver issue, so there's no real way I can diagnose this further.

We did some experimentation and the runtime is smart enough to recognise the error in the unmanaged code as a DivideByZeroException because of a specific interrupt it generates (#DE). For example, this throws the right exception:

struct div_t
{
    private int a;
    private int rem;
    public override string ToString()
    {
        return $"{a} rem {rem}";
    }
}
using var lib = new UnmanagedLibrary("MSVCR100.DLL");
Console.WriteLine(((delegate* unmanaged[Stdcall]<int, int, div_t>)lib.LoadFunction("div"))(100, 0));

So the problem is definitely with the driver. There's not much more help I can provide I'm afraid.

[muzapparjan]

It doesn't matter. Thank you for your time