ReadyToRun images compiled for Linux, macOS or the BSDs store the COFF machine XORed with IMAGE_FILE_MACHINE_NATIVE_OS_OVERRIDE (dotnet/runtime src/coreclr/inc/pedecoder.h). Every framework assembly in a Linux .NET install has machine 0xFD1D, so target admission and the managed PE reader rejected them as an unsupported architecture.
Decode the PE machine once in src/domain/peMachine.ts, replacing the two duplicated switches, and accept an OS override only on images with a CLI directory.
