Add DOTNET_DbgCreateDumpToolPath to override createdump directory (NativeAOT only)

[Copilot]

Description

Adds DOTNET_DbgCreateDumpToolPath environment variable to allow specifying a directory path where the createdump tool is located. In scenarios where createdump is not shipped with the NativeAOT runtime, users can now provide their own dump generation tool.

Note: This environment variable is only supported in NativeAOT applications and is ignored otherwise (not in other runtime configurations).

Implementation

• Modified PalCreateDumpInitialize() to check DOTNET_DbgCreateDumpToolPath for a directory path
• The runtime concatenates the directory path with "createdump" following the same pattern as the default behavior
• No file validation during initialization (aligned with commit c507305 which removed stat checks)
• Follows existing environment variable pattern using RhConfig::Environment::TryGetStringValue()
• Uses safe string handling with proper null-termination and buffer management
• Maintains backward compatibility: falls back to default behavior when not set

Usage

export DOTNET_DbgEnableMiniDump=1
export DOTNET_DbgCreateDumpToolPath=/path/to/directory
./myapp

The runtime will look for /path/to/directory/createdump

Customer Impact

Customers deploying NativeAOT in environments without createdump (custom distributions, minimal containers, embedded systems) currently cannot generate crash dumps. This prevents critical debugging in production scenarios.

Regression

No. This is a new opt-in feature with no impact on existing behavior. Only affects NativeAOT applications.

Testing

• NativeAOT runtime build verification (clr.nativeaotruntime)
• Code follows existing patterns for environment variable handling and memory management
• Documentation updated with usage examples and NativeAOT-only clarification using "ignored otherwise" wording to avoid ambiguity since NativeAOT uses a stripped-down version of CoreCLR
• Safe string handling verified

Risk

Low. New environment variable only used when explicitly set. Code path follows existing directory concatenation pattern used for default createdump lookup. No changes to existing dump generation logic. NativeAOT only, so no impact on other runtime configurations.

Original prompt

Using a new environment variable DOTNET_DbgCreateDumpToolPath, add the ability to override where we look for the createdump tool in the PalCreateDumpInitialize in PalCreateDump.cpp. In some scenarios we do not ship createdump and we should make it easier to 'bring your own' should one decide they need a dump.

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[Copilot]

Pull request overview

This pull request adds a new environment variable DOTNET_DbgCreateDumpToolPath to allow NativeAOT applications to specify a custom directory where the createdump tool is located. This addresses scenarios where createdump is not shipped with the NativeAOT runtime, enabling users to provide their own dump generation tool.

Changes:

• Modified PalCreateDumpInitialize() to check for DOTNET_DbgCreateDumpToolPath environment variable and use it to locate createdump
• Added if/else logic to support both custom path and default library-based path discovery
• Updated documentation to describe the new environment variable and its NativeAOT-only support

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/coreclr/nativeaot/Runtime/unix/PalCreateDump.cpp	Adds environment variable check and custom path handling for createdump tool location with proper memory management and path concatenation logic
docs/design/coreclr/botr/xplat-minidump-generation.md	Documents the new DOTNET_DbgCreateDumpToolPath environment variable with usage examples and NativeAOT-only clarification