[2.6 patch] remove support for gcc < 3.2

From: Adrian Bunk
Date: Sun Jul 31 2005 - 17:27:12 EST

This patch removes support for gcc < 3.2 .

The advantages are:
- reducing the number of supported gcc versions from 8 to 4 [1]
allows the removal of several #ifdef's and workarounds
- my impression is that the older compilers are only rarely
used, so miscompilations of a driver with an old gcc might
not be detected for a longer amount of time

My personal opinion about the time and space a compilation requires is
that this is no longer that much of a problem for modern hardware, and
in the worst case you can compile the kernels for older machines on more
recent machines.

This patch does not yet remove all the #ifdef's and other things that
are now no longer required, it only let's the compilation #error for
older gcc versions and updates the documentation.

I'd like to see this patch in the next -mm, and if noone will tell a
strong reason for keeping support for these gcc versions I'll send the
cleanups that are now.

[1] support removed: 2.95, 2.96, 3.0, 3.1
still supported: 3.2, 3.3, 3.4, 4.0

Signed-off-by: Adrian Bunk <bunk@xxxxxxxxx>


Documentation/Changes | 23 ++---------------------
README | 6 +++---
include/linux/compiler.h | 4 +---
3 files changed, 6 insertions(+), 27 deletions(-)

--- linux-2.6.13-rc4-mm1/include/linux/compiler.h.old 2005-07-31 19:07:34.000000000 +0200
+++ linux-2.6.13-rc4-mm1/include/linux/compiler.h 2005-07-31 19:08:24.000000000 +0200
@@ -40,10 +40,8 @@
#error no compiler-gcc.h file for this gcc version
#elif __GNUC__ == 4
# include <linux/compiler-gcc4.h>
-#elif __GNUC__ == 3
+#elif (__GNUC__ == 3 && __GNUC_MINOR__ >= 2)
# include <linux/compiler-gcc3.h>
-#elif __GNUC__ == 2
-# include <linux/compiler-gcc2.h>
# error Sorry, your compiler is too old/not recognized.
--- linux-2.6.13-rc4-mm1/README.old 2005-07-31 19:11:01.000000000 +0200
+++ linux-2.6.13-rc4-mm1/README 2005-07-31 19:11:38.000000000 +0200
@@ -174,9 +174,9 @@

COMPILING the kernel:

- - Make sure you have gcc 2.95.3 available.
- gcc 2.91.66 (egcs-1.1.2), and gcc are known to miscompile
- some parts of the kernel, and are *no longer supported*.
+ - Make sure you have gcc >= 3.2 available.
+ Older versions of gcc are *no longer supported*.
Also remember to upgrade your binutils package (for as/ld/nm and company)
if necessary. For more information, refer to Documentation/Changes.

--- linux-2.6.13-rc4-mm1/Documentation/Changes.old 2005-07-31 19:11:56.000000000 +0200
+++ linux-2.6.13-rc4-mm1/Documentation/Changes 2005-07-31 19:12:48.000000000 +0200
@@ -48,7 +48,7 @@
hardware, for example, you probably needn't concern yourself with

-o Gnu C 2.95.3 # gcc --version
+o Gnu C 3.2 # gcc --version
o Gnu make 3.79.1 # make --version
o binutils 2.12 # ld -v
o util-linux 2.10o # fdformat --version
@@ -75,26 +75,7 @@

The gcc version requirements may vary depending on the type of CPU in your
-computer. The next paragraph applies to users of x86 CPUs, but not
-necessarily to users of other CPUs. Users of other CPUs should obtain
-information about their gcc version requirements from another source.
-The recommended compiler for the kernel is gcc 2.95.x (x >= 3), and it
-should be used when you need absolute stability. You may use gcc 3.0.x
-instead if you wish, although it may cause problems. Later versions of gcc
-have not received much testing for Linux kernel compilation, and there are
-almost certainly bugs (mainly, but not exclusively, in the kernel) that
-will need to be fixed in order to use these compilers. In any case, using
-pgcc instead of plain gcc is just asking for trouble.
-The Red Hat gcc 2.96 compiler subtree can also be used to build this tree.
-You should ensure you use gcc-2.96-74 or later. gcc-2.96-54 will not build
-the kernel correctly.
-In addition, please pay attention to compiler optimization. Anything
-greater than -O2 may not be wise. Similarly, if you choose to use gcc-2.95.x
-or derivatives, be sure not to use -fstrict-aliasing (which, depending on
-your version of gcc 2.95.x, may necessitate using -fno-strict-aliasing).


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