Compiling lm_sensors module with gcc 3.3. (A problem and workaround.)

[ishikawa@yk.rim.or.jp (Chiaki)]

Compiling lm_sensors module with gcc 3.3.

Hi,

Thank you for the great software packages (LM_SENSORS and I2C.)

This is a short bug report and workaround caused by
the latest GCC 3.3.

Background.

Recently, I upgraded GCC on my Debian GNU/Linux PC to GCC 3.3.
After that I upgraded linux kernel to 2.4.21.

Obviously, GCC 3.3 broke some assumptions that the earlier
gcc 2.9.x kept, and so
lm_sensors 2.7.0 could not be compiled right away.

PROBLEM:

Basically the problem is this.

GCC 3.3 no longer honors the user's wish to
use -I/usr/local/include/ FIRST prior to system header directories.
(It seems that many people were bitten with mixup
verson of system headers in such directories , and it seems that
GCC 3.3 now has an internal list of so called "system header
directory" which had been the standard places for such
quasi-system headers for temporary tool development, etc.
GCC now refuses to honor the inclusion of -Isuch_header_directory
on the command line. (It prints out that it is ignoring
such directory  due to this. So far, so good.

Problem is that
/usr/local/include is such an ignored header directory!

This poses a problem for lm_sensors compilation since
the compilation needs to look at the latest i2c headers
in the /usr/local/include/linux/l2c.h and other files
under the directory instead of the outdated i2c header files under
kernel header directory.

WORKAROUND:

After scratching my head for a while and many false starts,
I finally decided to the following and
the compilation now succeeds.

You might want to put a comment regarding this in
your INSTALL file.

1. Create a new directory to store i2c header files.
   I chose

      /usr/local/tool-include

  This must not collide with the gcc's blacklisted system header
  directory and the above choice is OK.

2. Change i2c top-level Make file so tthat the latest
   i2c headers are stored in the directory created above.


*** Makefile~	2002-12-05 00:44:32.000000000 +0900
--- Makefile	2003-06-22 07:08:39.000000000 +0900
***************
*** 73,79 ****
  # This is the directory into which the header files will be installed.
  # If you want to make sure your current kernel tree is not overwritten,
  # the default should work. This is ignored for the i2c build system.
! LINUX_INCLUDE_DIR := /usr/local/include/linux
  #LINUX_INCLUDE_DIR := $(LINUX_HEADERS)/linux

  # If you want to isntall everything at some other place then at which
--- 73,79 ----
  # This is the directory into which the header files will be installed.
  # If you want to make sure your current kernel tree is not overwritten,
  # the default should work. This is ignored for the i2c build system.
! LINUX_INCLUDE_DIR := /usr/local/tool-include/linux
  #LINUX_INCLUDE_DIR := $(LINUX_HEADERS)/linux

  # If you want to isntall everything at some other place then at which


  run make install to install the headers into the directory.


3. Change lm_sensors top level makefile so that it will look
   for the i2c headers thus stored.


*** Makefile~	2002-12-05 00:44:32.000000000 +0900
--- Makefile	2003-06-22 07:22:38.000000000 +0900
***************
*** 49,55 ****
  # may be used mistakenly. Note: This should point to the directory
  # *above* the linux/ subdirectory, so to /usr/local/include in the
  # above example.
! I2C_HEADERS=/usr/local/include
  #I2C_HEADERS=$(LINUX_HEADERS)

  # Uncomment the third line on SMP systems if the magic invocation
fails. It
--- 49,55 ----
  # may be used mistakenly. Note: This should point to the directory
  # *above* the linux/ subdirectory, so to /usr/local/include in the
  # above example.
! I2C_HEADERS=/usr/local/tool-include
  #I2C_HEADERS=$(LINUX_HEADERS)

  # Uncomment the third line on SMP systems if the magic invocation
fails. It


4. With the above change, the compilation of lm_sensors succeeds
and I could install lm_sensors modules with gcc 3.3.


Thank you again for the great piece of software.

Happy Hacking

Ishikawa, Chiaki


PS: The ignoring of "system header" directory used as part of -I
parameter by the latest gcc is a blessing to some obviously [
I can certainly think of some scenarios of long debug sessions
of a bug caused by the mixup of different version header files ]
but to
those who knew what we were doing by the sleight of hands (so to
speak),
this GCC  change causes an initial pain until all the tool chains are
modified.
We can't win always, it seems.



-- 
int main(void){int j 03;/*(c)2003 cishikawa. */
char t[] ="<CI> @abcdefghijklmnopqrstuvwxyz.,\n\"";
char *i ="g>qtCIuqivb,gCwe\np@.ietCIuqi\"tqkvv is>dnamz";
while(*i)((j+=strchr(t,*i++)-(int)t),(j%=sizeof t-1),
(putchar(t[j])));return 0;}/* under GPL */