Willy Tarreau (on Fri, 1 Dec 2006 06:26:53 +0100) wrote:
>On Fri, Dec 01, 2006 at 04:14:04PM +1100, Keith Owens wrote:
>> SuSE's SLES10 ships with gcc 4.1.0. There is nothing to stop a
>> distributor from backporting the bug fix from gcc 4.1.1 to 4.1.0, but
>> this patch would not allow the fixed compiler to build the kernel.
>
>Then maybe replace #error with #warning ? It's too dangerous to let people
>build their kernel with a known broken compiler without being informed.
Agreed.
>I think this shows the limit of backports to known broken versions.
>Providing a full update to 4.1.1 would certainly be cleaner for all
>customers than backporting 4.1.1 to 4.1.0 and calling it 4.1.0.
Agreed, but Enterprise customers expect bug fixes, not wholesale
replacements of critical programs.
>Another solution would be to be able to check gcc for known bugs in the
>makefile, just like we check it for specific options. But I don't know
>how we can check gcc for bad code, especially in cross-compile environments
It is doable, but it is as ugly as hell. Note the lack of a
signed-off-by :)
---
arch/i386/kernel/Makefile | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
Index: linux/arch/i386/kernel/Makefile
===================================================================
--- linux.orig/arch/i386/kernel/Makefile
+++ linux/arch/i386/kernel/Makefile
@@ -83,3 +83,19 @@ $(obj)/vsyscall-syms.o: $(src)/vsyscall.
k8-y += ../../x86_64/kernel/k8.o
stacktrace-y += ../../x86_64/kernel/stacktrace.o
+# Some versions of gcc generate invalid code for hpet_timer, depending
+# on other config options. Make sure that the generated code is valid.
+# Invalid versions of gcc generate a tight loop in wait_hpet_tick, with
+# no 'cmp' instructions. Extract the generated object code for
+# wait_hpet_tick, down to the next function then check that the code
+# contains at least one comparison.
+
+ifeq ($(CONFIG_HPET_TIMER),y)
+$(obj)/built-in.o: $(obj)/.tmp_check_gcc_bug
+
+$(obj)/.tmp_check_gcc_bug: $(obj)/time_hpet.o
+ $(Q)[ -n "`$(OBJDUMP) -Sr $< | grep -A40 '<wait_hpet_tick>:' | sed -e '1d; />:$$/,$$d;' | grep -w cmp`" ] || \
+ (echo gcc volatile bug detected, fix your gcc; exit 1)
+ $(Q)touch $@
+
+endif
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
