[src/trunk]: src/lib/csu Add some more clues on what is needed to add a new p...

[joerg <joerg%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ed27ceccdcc8
branches:  trunk
changeset: 787568:ed27ceccdcc8
user:      joerg <joerg%NetBSD.org@localhost>
date:      Mon Jun 24 14:27:35 2013 +0000

description:
Add some more clues on what is needed to add a new platform.

diffstat:

 lib/csu/README |  21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diffs (28 lines):

diff -r e1bf9770e1fa -r ed27ceccdcc8 lib/csu/README
--- a/lib/csu/README    Mon Jun 24 12:56:22 2013 +0000
+++ b/lib/csu/README    Mon Jun 24 14:27:35 2013 +0000
@@ -1,3 +1,24 @@
+Introduction
+
+This document covers the native NetBSD compiler runtime. The full support
+for the native runtime is enabled by setting USE_COMPILERCRTSTUFF to no
+in bsd.own.mk.
+
+Machine independent sources can be found in common. The crtbegin.c in
+that directory is a useful template for deriving compact assembler
+versions. That is preferable to decouple the result from changes in the
+compiler logic.
+
+A new platform should provide the following content in
+arch/${MACHINE_ARCH} or arch/${MACHINE_CPU}:
+- Makefile.inc: provides ELFSIZE corresponding to 32/64bit file format
+- crt0.S: provides setup code and the call to __start.
+- crtbegin.S: see below
+- crtend.S: see below, most likely just a copy of an existing architecture
+- crti.S: prefix part of .init/.fini sections, i.e. to ensure stack alignment
+- crte.S: suffix part of the .init/.fini sections, i.e. return to caller.
+
+
 Overview of the common runtime support
 
 The common runtime support contains two modules, crtbegin and crtend.