Add SPI Master driver, example, test and docs

[esp-idf] / docs / build_system.rst

diff --git a/docs/build_system.rst b/docs/build_system.rst
index 4ba89f8652fec06b806d44b5ec032e18eb9a0281..6687fa69ed2f8d70fa4ccb2a583052dc1bcb107e 100644 (file)
--- a/docs/build_system.rst
+++ b/docs/build_system.rst
@@ -188,6 +188,10 @@ The following variables can be set inside ``component.mk`` to control build sett
   are available at all times. It is necessary if one component
   generates an include file which you then want to include in another
   component. Most components do not need to set this variable.
+- ``COMPONENT_ADD_LINKER_DEPS``: Optional list of component-relative paths
+  to files which should trigger a re-link of the ELF file if they change.
+  Typically used for linker script files and binary libraries. Most components do
+  not need to set this variable.
 
 The following variable only works for components that are part of esp-idf itself:
 
@@ -245,6 +249,12 @@ The following variables can be set inside ``component.mk`` to control the build
   +=``. It is also possible (although not recommended) to override
   this variable completely for a component.
 
+To apply compilation flags to a single source file, you can add a variable override as a target, ie::
+
+  apps/dhcpserver.o: CFLAGS += -Wno-unused-variable
+
+This can be useful if there is upstream code that emits warnings.
+
 Component Configuration
 -----------------------