From a116313d5425b8b72729e881bf71a07876b8db86 Mon Sep 17 00:00:00 2001
From: "Mark M. Hoffman" <mhoffman@lightlink.com>
Date: Sun, 18 Sep 2005 20:39:53 +0000
Subject: [PATCH] (mmh) This patch makes optional the sysfs support in
 libsensors.  The default is to *disable* sysfs support if a 2.4.x kernel is
 detected, for all other versions, support will be enabled.  This can be
 overridden in the top-level Makefile.

git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@3096 7894878c-1315-0410-8ee3-d5d059ff63e0
---
 Makefile      | 19 +++++++++++++++++++
 lib/Module.mk | 11 ++++++++++-
 lib/sysfs.h   | 10 ++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index bf2235f0..a01243c9 100644
--- a/Makefile
+++ b/Makefile
@@ -86,6 +86,19 @@ CC := gcc
 #   /lib/modules/2.4.29
 MODPREF := /lib/modules/$(shell $(CC) -I$(LINUX_HEADERS) -E etc/config.c | grep uts_release |cut -f 2 -d'"')
 
+# When building userspace for use with 2.4.x series kernels, we turn off
+# sysfs support by default.  You can override this (e.g. if you want
+# to build binaries that work for both 2.4.x, and 2.6.x and above)
+# by uncommenting the line after the next endif.  Keep in mind, if and only
+# if you do this: you will need to install the libsysfs libraries on your
+# kernel 2.4.x systems also.
+ifeq (,$(findstring /2.4., $(MODPREF)))
+	SYSFS_SUPPORT := 1
+else
+	SYSFS_SUPPORT :=
+endif
+#SYSFS_SUPPORT := 1
+
 # Prevent 2.6+ users from using improper targets, as this won't work.
 ifeq (,$(findstring /2.4., $(MODPREF)))
     ifeq (, $(MAKECMDGOALS))
@@ -257,8 +270,14 @@ MODCFLAGS += $(ALL_CFLAGS)
 PROGCPPFLAGS := -DETCDIR="\"$(ETCDIR)\"" $(ALL_CPPFLAGS) -Wundef
 PROGCFLAGS := $(ALL_CFLAGS)
 ARCPPFLAGS := $(ALL_CPPFLAGS)
+ifdef SYSFS_SUPPORT
+ARCPPFLAGS := $(ARCPPFLAGS) -DSYSFS_SUPPORT
+endif
 ARCFLAGS := $(ALL_CFLAGS)
 LIBCPPFLAGS := $(ALL_CPPFLAGS)
+ifdef SYSFS_SUPPORT
+LIBCPPFLAGS := $(LIBCPPFLAGS) -DSYSFS_SUPPORT
+endif
 LIBCFLAGS := -fpic $(ALL_CFLAGS)
 
 .PHONY: all clean install version package dep
diff --git a/lib/Module.mk b/lib/Module.mk
index a8500292..9a507aa0 100644
--- a/lib/Module.mk
+++ b/lib/Module.mk
@@ -49,7 +49,11 @@ LIBTARGETS := $(MODULE_DIR)/$(LIBSTLIBNAME) $(MODULE_DIR)/$(LIBSHLIBNAME) \
 LIBCSOURCES := $(MODULE_DIR)/data.c $(MODULE_DIR)/general.c \
                $(MODULE_DIR)/error.c $(MODULE_DIR)/chips.c \
                $(MODULE_DIR)/proc.c $(MODULE_DIR)/access.c \
-               $(MODULE_DIR)/init.c $(MODULE_DIR)/sysfs.c
+               $(MODULE_DIR)/init.c
+ifdef SYSFS_SUPPORT
+	LIBCSOURCES := $(LIBCSOURCES) $(MODULE_DIR)/sysfs.c
+endif
+
 LIBOTHEROBJECTS := $(MODULE_DIR)/conf-parse.o $(MODULE_DIR)/conf-lex.o
 LIBSHOBJECTS := $(LIBCSOURCES:.c=.lo) $(LIBOTHEROBJECTS:.o=.lo)
 LIBSTOBJECTS := $(LIBCSOURCES:.c=.ao) $(LIBOTHEROBJECTS:.o=.ao)
@@ -60,8 +64,13 @@ LIBHEADERFILES := $(MODULE_DIR)/error.h $(MODULE_DIR)/sensors.h \
                   $(MODULE_DIR)/chips.h
 
 # How to create the shared library
+ifdef SYSFS_SUPPORT
 $(MODULE_DIR)/$(LIBSHLIBNAME): $(LIBSHOBJECTS)
 	$(CC) -shared -Wl,-soname,$(LIBSHSONAME) -o $@ $^ -lc -lm -lsysfs
+else
+$(MODULE_DIR)/$(LIBSHLIBNAME): $(LIBSHOBJECTS)
+	$(CC) -shared -Wl,-soname,$(LIBSHSONAME) -o $@ $^ -lc -lm
+endif
 
 $(MODULE_DIR)/$(LIBSHSONAME): $(MODULE_DIR)/$(LIBSHLIBNAME)
 	$(RM) $@
diff --git a/lib/sysfs.h b/lib/sysfs.h
index 331307ad..216af73b 100644
--- a/lib/sysfs.h
+++ b/lib/sysfs.h
@@ -20,6 +20,7 @@
 #ifndef SENSORS_LIB_SYSFS_H
 #define SENSORS_LIB_SYSFS_H
 
+#ifdef SYSFS_SUPPORT
 extern int sensors_found_sysfs;
 
 extern char sensors_sysfs_mount[];
@@ -30,4 +31,13 @@ extern int sensors_read_sysfs_chips(void);
 
 extern int sensors_read_sysfs_bus(void);
 
+#else
+
+#define sensors_found_sysfs 0
+#define sensors_init_sysfs()
+#define sensors_read_sysfs_chips() (-1)
+#define sensors_read_sysfs_bus() (-1)
+
+#endif
+
 #endif /* !SENSORS_LIB_SYSFS_H */