Examining thread-local storage with GDB

How does one display variables in TLS?  I see nothing about this in
the manual.

What happened to me was that an attempt to display the value of a
thread-local variable was responded with some confusing message like
"No global value for this variable" (or something, I don't remember
the exact wording and couldn't find it in the sources), and it took a
long time (including looking at disassembly) to figure out this has
something to do with TLS.  Once I had that figured out, I still cannot
find any way of displaying the value, though.

What am I missing?

TIA