On Tue, Oct 18, 2022 at 5:16 PM Jiri Slaby <jirislaby@xxxxxxxxxx> wrote: > > Hi, > > On 24. 09. 22, 20:19, Masahiro Yamada wrote: > > Kbuild puts the objects listed in head-y at the head of vmlinux. > > Conventionally, we do this for head*.S, which contains the kernel entry > > point. > > > > A counter approach is to control the section order by the linker script. > > Actually, the code marked as __HEAD goes into the ".head.text" section, > > which is placed before the normal ".text" section. > > > > I do not know if both of them are needed. From the build system > > perspective, head-y is not mandatory. If you can achieve the proper code > > placement by the linker script only, it would be cleaner. > > > > I collected the current head-y objects into head-object-list.txt. It is > > a whitelist. My hope is it will be reduced in the long run. > > > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > ... > > --- a/Makefile > > +++ b/Makefile > > @@ -1149,10 +1149,10 @@ quiet_cmd_ar_vmlinux.a = AR $@ > > cmd_ar_vmlinux.a = \ > > rm -f $@; \ > > $(AR) cDPrST $@ $(KBUILD_VMLINUX_OBJS); \ > > - $(AR) mPiT $$($(AR) t $@ | head -n1) $@ $(head-y) > > + $(AR) mPiT $$($(AR) t $@ | head -n1) $@ $$($(AR) t $@ | grep -F --file=$(srctree)/scripts/head-object-list.txt) > > With AR=gcc-ar, the "| head -n1" results in: > /usr/lib64/gcc/x86_64-suse-linux/7/../../../../x86_64-suse-linux/bin/ar > terminated with signal 13 [Broken pipe] > > I found out only with gcc-lto. But maybe we should make it silent in any > case? I'm not sure how. This looks ugly (and needs the whole output to > be piped): > gcc-ar t vmlinux.a | ( head -n1; cat >/dev/null ) > > Note the result appears to be correct, it's only that gcc-ar complains > after printing out the very first line. Indeed, I see the same message. sed does not show such an error, though. masahiro@zoe:~/ref/linux$ gcc-ar t vmlinux.a | head -n1 arch/x86/kernel/head_64.o /usr/bin/ar terminated with signal 13 [Broken pipe] masahiro@zoe:~/ref/linux$ gcc-ar t vmlinux.a | sed -n 1p arch/x86/kernel/head_64.o -- Best Regards Masahiro Yamada
