On Tue, 24 Nov 2015 03:12:31 +0100,
Andi Kleen wrote:
>
> > > 5.x is better than 4.x but it's still a slower. It's also not incremential.
> >
> > At the last time I tested with the latest 5.x and stock binutils on
> > openSUSE Tumbleweed, I failed to build, unfortunately. Partly the
> > detection of gcc version doesn't work for 5.x, and partly something is
>
> Really? It work for me with gcc 5
I retested now, and it seems like only the binutils, not about gcc
version, indeed. Sorry for confusion.
> > missing in binutils side, although it's already built with plugin.
>
> Yes it needs HJ Lu's Linux binutils, not the standard FSF binutils.
> The patch to fix LTO with ld -r was submitted to standard binutils, but they
> didn't want to fix the issue.
I did "make allnoconfig", disabled tracers, gcov, etc, and then
enabled LTO. With hlj version, the build reaches to the almost end
hitting this:
LD vmlinux
arch/x86/kernel/cpu/perf_event_intel_rapl.c:66:20: error: rapl_domain_names causes a section type conflict with __setup_str_set_reset_devices
static const char *rapl_domain_names[NR_RAPL_DOMAINS] __initconst = {
^
init/main.c:159:19: note: ‘__setup_str_set_reset_devices’ was declared here
__setup("reset_devices", set_reset_devices);
Hmm... I see no direct relation, but OK, let's try to get rid of
__initconst. Now it hits lots of other errors like:
`__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)
`__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)
`__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)
`__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)
/tmp/ccUCMU7n.ltrans21.ltrans.o: In function `do_exit':
<artificial>:(.text+0xfc0): undefined reference to `sys_futex'
/tmp/ccUCMU7n.ltrans22.ltrans.o: In function `_do_fork':
<artificial>:(.text+0x39f7): undefined reference to `ret_from_fork'
<artificial>:(.text+0x4428): undefined reference to `ret_from_kernel_thread'
....
Any hints to solve these?
thanks,
Takashi
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