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[UML] fix gcc ICEs and unresolved externs

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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 c0a18111e5

Ingo reported a gcc internal error with gcc 4.3 with no-unit-at-a-timem,
resulting in 22eecde2f9

Benny Halevy 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>
Cc: Benny Halevy <bhalevy@panasas.com>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jeff Dike 2008-07-07 13:36:56 -04:00 committed by Linus Torvalds
parent b2798bf0ec
commit 4f81c5350b
3 changed files with 10 additions and 1 deletions
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1
arch/um/Makefile
View File

@ -77,7 +77,6 @@ include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
KERNEL_DEFINES = $(strip -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask \
-Dmktime=kernel_mktime $(ARCH_KERNEL_DEFINES))
KBUILD_CFLAGS += $(KERNEL_DEFINES)
KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time,)
PHONY += linux

7
arch/um/Makefile-i386
View File

@ -32,4 +32,11 @@ cflags-y += $(call cc-option,-mpreferred-stack-boundary=2)
# 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)

3
arch/um/Makefile-x86_64
View File

@ -21,3 +21,6 @@ HEADER_ARCH := x86
LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib64
LINK-y += -m64
# Do unit-at-a-time unconditionally on x86_64, following the host
KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)