From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 14 Nov 2019 15:43:14 +0000 (+0000)
Subject: docs: Discuss variable settings and inclusion order
X-Git-Tag: subdirmk/0.1~9
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?p=subdirmk.git;a=commitdiff_plain;h=c0b216c79763f720df20e002fc14c9348a0e05c2;hp=f51d1785a6b1266cc4aa475b53930e673b46f98e;ds=sidebyside

docs: Discuss variable settings and inclusion order

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/README b/README
index c9e4c0f..cfd7ad0 100644
--- a/README
+++ b/README
@@ -105,6 +105,19 @@ is already provided in subdirmk, for you to reference like this:
   &:include subdirmk/clean.sd.mk
 For example you could put that in Perdir.sd.mk.
 
+The top-level Subdir.sd.mk is the first makefile included after the
+autogenerated `main.mk' which merely has some basic settings and
+includes.  So if you want to get in early and set global variables,
+put them near the top of Subdir.sd.mk.
+
+subdirmk's filter script itself sets (only) these variables:
+  top_srcdir
+  abs_top_srcdir
+  SUBDIRMK_MAKEFILES
+  MAKEFILE_TEMPLATES
+You are likely to want to define $(PWD), and shorter names for
+top_srdir and abs_top_srcdir (we suggest $(src) and $(abs_src)).
+
 Global definitions
 ------------------