[PATCH] docs/tcg-plugins: document QEMU_PLUGIN behaviour

[Christoph Muellner]

QEMU plugins can be loaded via command line arguments or via
the QEMU_PLUGIN environment variable. Currently, only the first method
is documented. Let's document QEMU_PLUGIN.

Signed-off-by: Christoph Muellner <cmuellner@linux.com>
---
 docs/devel/tcg-plugins.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst
index f93ef4fe52..ba48be18d0 100644
--- a/docs/devel/tcg-plugins.rst
+++ b/docs/devel/tcg-plugins.rst
@@ -34,6 +34,10 @@ Arguments are plugin specific and can be used to modify their
 behaviour. In this case the howvec plugin is being asked to use inline
 ops to count and break down the hint instructions by type.
 
+QEMU also evaluates the environment variable ``QEMU_PLUGIN``::
+
+  QEMU_PLUGIN="file=tests/plugin/libhowec.so,inline=on,count=hint" $QEMU
+
 Writing plugins
 ---------------
 
-- 
2.35.1