src/doc/unstable-book/src/compiler-flags/tls-model.md
tls_modelThe tracking issue for this feature is: None.
Option -Z tls-model controls TLS model used to
generate code for accessing #[thread_local] static items.
Supported values for this option are:
global-dynamic - General Dynamic TLS Model (alternatively called Global Dynamic) is the most
general option usable in all circumstances, even if the TLS data is defined in a shared library
loaded at runtime and is accessed from code outside of that library.
This is the default for most targets.local-dynamic - model usable if the TLS data is only accessed from the shared library or
executable it is defined in. The TLS data may be in a library loaded after startup (via dlopen).initial-exec - model usable if the TLS data is defined in the executable or in a shared library
loaded at program startup.
The TLS data must not be in a library loaded after startup (via dlopen).local-exec - model usable only if the TLS data is defined directly in the executable,
but not in a shared library, and is accessed only from that executable.emulated - Uses thread-specific data keys to implement emulated TLS.
It is like using a general-dynamic TLS model for all modes.rustc and LLVM may use a more optimized model than specified if they know that we are producing
an executable rather than a library, or that the static item is private enough.