Re: [patch] Re: Kernels > 2.6.1-mm3 do not boot. - SOLVED

[Andrew Morton <akpm@osdl.org>]

Andi Kleen <ak@muc.de> wrote:
>
> > I'll turn it on for gcc-3.3 and higher.  We can change that if someone has
> > tested earlier compilers.
> 
> Earlier compilers never supported -funit-at-a-time. The option 
> was first implemented in gcc 3.3-hammer and later merged into 3.4.

OK, then let's use check-gcc again.

> > Also, I do think this should remain a per-arch decision.  Other
> > architectures could well have similar problems to this and we don't want to
> > be mysteriously breaking their kernels for them.
> 
> That's fine by me. While you're at it could you enable it for x86-64 too?

yup.


diff -puN arch/i386/Makefile~use-funit-at-a-time arch/i386/Makefile
--- 25/arch/i386/Makefile~use-funit-at-a-time	Tue Jan 27 15:40:09 2004
+++ 25-akpm/arch/i386/Makefile	Tue Jan 27 15:42:26 2004
@@ -73,6 +73,10 @@ cflags-$(CONFIG_X86_ELAN)	:= -march=i486
 GCC_VERSION			:= $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
 cflags-$(CONFIG_REGPARM) 	+= $(shell if [ $(GCC_VERSION) -ge 0300 ] ; then echo "-mregparm=3"; fi ;)
 
+# Enable unit-at-a-time mode when possible. It shrinks the
+# kernel considerably.
+CFLAGS += $(call check_gcc,-funit-at-a-time,)
+
 CFLAGS += $(cflags-y)
 
 # Default subarch .c files
diff -puN arch/x86_64/Makefile~use-funit-at-a-time arch/x86_64/Makefile
--- 25/arch/x86_64/Makefile~use-funit-at-a-time	Tue Jan 27 15:42:34 2004
+++ 25-akpm/arch/x86_64/Makefile	Tue Jan 27 15:44:44 2004
@@ -52,7 +52,10 @@ CFLAGS += -Wno-sign-compare
 ifneq ($(CONFIG_DEBUG_INFO),y)
 CFLAGS += -fno-asynchronous-unwind-tables
 endif
-#CFLAGS += $(call check_gcc,-funit-at-a-time,)
+
+# Enable unit-at-a-time mode when possible. It shrinks the
+# kernel considerably.
+CFLAGS += $(call check_gcc,-funit-at-a-time,)
 
 head-y := arch/x86_64/kernel/head.o arch/x86_64/kernel/head64.o arch/x86_64/kernel/init_task.o
 

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