Messages in this thread | | | Date | Tue, 18 Oct 2022 10:16:20 +0200 | Subject | Re: [PATCH v3 7/7] kbuild: remove head-y syntax | From | Jiri Slaby <> |
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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@kernel.org> ... > --- 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.
thanks, -- js suse labs
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