使用较新的编译器编译linux 2.6内核模块

Question

I build embedded machines that run an RT_PREMPT version of Linux. It's an Ubuntu 10.04 installation running an Linux 2.6 kernel. Yes, it's an old kernel, but I'm stuck with it for awhile.

When I compiled the kernel, I used gcc version 4.4. On this system, there is a kernel module I have been compiling successfully for three years.

From my Makefile...

all:

make -C /lib/modules/$(shell uname -r)/build M=$(PWD) \
    modules

My current project requires support for c++14, so I updated gcc and g++ to version 5.1.0 by building from source. All my user-mode software compiles, but when I went to build an updated version of my kernel module, I get the following error right away:

make[1]: Entering directory `/usr/src/linux-headers-2.6.32-54-generic'
  CC [M]  /home/tbj/srcroot/ctsengine-hg/CtsRt/ctsrt_main.o
In file included from include/linux/compiler.h:40:0,
             from include/linux/stddef.h:4,
             from include/linux/list.h:4,
             from include/linux/module.h:9,
             from /home/tbj/srcroot/ctsengine-hg/CtsRt/ctsrt_main.c:31:
include/linux/compiler-gcc.h:86:30: fatal error: linux/compiler-gcc5.h: No such file or directory

In short:

fatal error: linux/compiler-gcc5.h: No such file or directory

If I use gcc 4.4 again (I left it installed on my computer in a different directory), it compiles and runs perfectly.

Obviously, I'm missing something. Is it not possible to compile a kernel module with a newer version of the compiler than what the operating system was compiled with? That seems unlikely to me. Is there a configuration step I'm missing? Is there a system variable I need to update? Are there extra headers I'm supposed to download? I ran apt to update build-essential, but it was up to date. I have the source and headers for the kernel on my system. I'm not sure what else I would download.

Any insights to this problem are greatly appreciated. Thank you in advance.

Answer 1

Your kernel version is too old and it is missing linux/compiler-gcc5.h .

The header is included from linux/compiler-gcc.h and its name is generated by preprocessor macro based on current compiler version:

#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)

This header was introduced around version 3.18 .

You might try to get this file from a newer kernel source and put in into include/linux .

Answer 2

Open a terminal and type:

$ ls -r /usr/src/linux-headers-$(uname -r)/include/linux/ | \
  grep -P "compiler-gcc\d.h" | \
  head -n 1

this will hopefully output the latest gcc header suitable for your linux kernel.

In my case it is compiler-gcc4.h . Now you can link this file to compiler-gcc5.h in the following way:

$ sudo ln -s /usr/src/linux-headers-$(uname -r)/include/linux/compiler-gcc4.h \
             /usr/src/linux-headers-$(uname -r)/include/linux/compiler-gcc5.h