Windows arm64 support

[adamsitnik]

Are there any plans for adding Windows arm64 support?

Currently I can't attach to an arm64 process on Windows due to missing DAC.

Context: we have recently implemented an arm64 disassembler for BenchmarkDotNet and it works great on Linux, but does not on Windows. It would be nice to have it working too.

[leculver]

What's the error you are getting? AFAIK this should work, but I don't have an arm64 machine handy. All of the requisite pieces should be there, but I've never tested it.

[adamsitnik]

System.IO.FileNotFoundException: 'Could not find matching DAC for this runtime.'
   at Microsoft.Diagnostics.Runtime.ClrInfo.CreateRuntime()

[leculver]

Sorry, I've been heads down for the last few weeks. I'm now a bit more free to look at issues.

System.IO.FileNotFoundException: 'Could not find matching DAC for this runtime.'
   at Microsoft.Diagnostics.Runtime.ClrInfo.CreateRuntime()

If this is a crash dump, can you please share it with me offline?

I assume this is a live process though, right? Is there an Arm64 machine you can share credentials with me (offline) so I can go investigate this with a debugger?

[k15tfu]

@leculver Hi! I faced with the same issue, this happens because of:

clrmd/src/Microsoft.Diagnostics.Runtime/DataReaders/Windows/WindowsProcessDataReader.cs

Line 134 in 0c46ba9

public Architecture Architecture => IntPtr.Size == 4 ? Architecture.X86 : Architecture.X64;

, so the corresponding DebugLibraryInfo for shared\Microsoft.NETCore.App\7.0.10\mscordaccore.dll has TargetArchitecture which is equal to Amd64:

clrmd/src/Microsoft.Diagnostics.Runtime/ClrInfo.cs

Line 149 in 0c46ba9

artifacts.Insert(0, dacLibraryInfo);

Besides, looks like WindowsProcessDataReader.GetThreadContext() should also support ARM64Context:

clrmd/src/Microsoft.Diagnostics.Runtime/DataReaders/Windows/WindowsProcessDataReader.cs

Lines 202 to 227 in 0c46ba9

	public bool GetThreadContext(uint threadID, uint contextFlags, Span<byte> context)
	{
	// We need to set the ContextFlags field to be the value of contextFlags. For AMD64, that field is
	// at offset 0x30. For all other platforms that field is at offset 0. We test here whether the context
	// is large enough to write the flags and then assign the value based on the architecture's offset.
	bool amd64 = Architecture == Architecture.X64;
	if (context.Length < 4 || (amd64 && context.Length < 0x34))
	return false;
	if (amd64)
	{
	fixed (byte* ptr = context)
	{
	AMD64Context* ctx = (AMD64Context*)ptr;
	ctx->ContextFlags = contextFlags;
	}
	}
	else
	{
	fixed (byte* ptr = context)
	{
	uint* intPtr = (uint*)ptr;
	*intPtr = contextFlags;
	}
	}

Please tell me if you need anything else.

[leculver]

Thank you! This is extremely helpful.