ReadyToRun compiler doesn't support cross-targeting. You must compile on a given target. For example, if you want R2R images for Windows x64, you need to run the publish command on that environment.
Exceptions to cross-targeting:
For some SDK platforms, the ReadyToRun compiler is capable of cross-compiling for other target platforms. Supported compilation targets are described in the below table.
|SDK platform||Supported target platforms|
|Windows X64||Windows X86, Windows X64, Windows ARM32, Windows ARM64|
|Windows X86||Windows X86, Windows ARM32|
|Linux X64||Linux X86, Linux X64, Linux ARM32, Linux ARM64|
|Linux ARM32||Linux ARM32|
|Linux ARM64||Linux ARM64|
|macOS X64||macOS X64|