[ This patch needs to get into 2.6.26 ]
There are various constraints on the use of unit-at-a-time:
i386 uses no-unit-at-a-time for pre-4.0 (not 4.3)
x86_64 uses unit-at-a-time always
Uli reported a crash on x86_64 with gcc 4.1.2 with
unit-at-a-time, resulting in commit c0a18111e571138747a98af18b3a2124df56a0d1
Ingo reported a gcc internal error with gcc 4.3 with
no-unit-at-a-timem, resulting in 22eecde2f9034764a3fd095eecfa3adfb8ec9a98
Benny Halevy <bhalevy@panasas.com> is seeing extern inlines
not resolved with gcc 4.3 with no-unit-at-a-time
This patch reintroduces unit-at-a-time for gcc >= 4.0, bringing back
the possibility of Uli's crash. If that happens, we'll debug it.
I started seeing both the internal compiler errors and unresolved
inlines on Fedora 9. This patch fixes both problems, without so far
reintroducing the crash reported by Uli.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
---
arch/um/Makefile | 1 -
arch/um/Makefile-i386 | 7 +++++++
arch/um/Makefile-x86_64 | 3 +++
3 files changed, 10 insertions(+), 1 deletion(-)
Index: linux-2.6.22/arch/um/Makefile-i386
===================================================================
--- linux-2.6.22.orig/arch/um/Makefile-i386 2008-05-29 11:21:25.000000000 -0400
+++ linux-2.6.22/arch/um/Makefile-i386 2008-07-07 13:11:10.000000000 -0400
@@ -32,4 +32,11 @@ cflags-y += $(call cc-option,-mpreferred
# an unresolved reference.
cflags-y += -ffreestanding
+# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use
+# a lot more stack due to the lack of sharing of stacklots. Also, gcc
+# 4.3.0 needs -funit-at-a-time for extern inline functions.
+KBUILD_CFLAGS += $(shell if [ $(call cc-version) -lt 0400 ] ; then \
+ echo $(call cc-option,-fno-unit-at-a-time); \
+ else echo $(call cc-option,-funit-at-a-time); fi ;)
+
KBUILD_CFLAGS += $(cflags-y)
Index: linux-2.6.22/arch/um/Makefile-x86_64
===========================...
