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.
thanks,
--
js
suse labs
