2021-08-14 23:42:56

by Masahiro Yamada

Subject: [PATCH] kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y

When CONFIG_TRIM_UNUSED_KSYMS is enabled, I see some warnings like this:

nm: arch/x86/entry/vdso/vdso32/note.o: no symbols

$NM (both GNU nm and llvm-nm) warns when no symbol is found in the
object. Suppress the stderr.

Fixes: bbda5ec671d3 ("kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS")
Signed-off-by: Masahiro Yamada <[email protected]>
---

scripts/gen_ksymdeps.sh | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/scripts/gen_ksymdeps.sh b/scripts/gen_ksymdeps.sh
index 1324986e1362..5493124e8ee6 100755
--- a/scripts/gen_ksymdeps.sh
+++ b/scripts/gen_ksymdeps.sh
@@ -4,7 +4,10 @@
set -e

# List of exported symbols
-ksyms=$($NM $1 | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
+#
+# If the object has no symbol, $NM warns 'no symbols'.
+# Suppress the stdout.
+ksyms=$($NM $1 2>/dev/null | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)

if [ -z "$ksyms" ]; then
exit 0
--
2.30.2

2021-08-15 01:17:33

by Nathan Chancellor

Subject: Re: [PATCH] kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y

On 8/14/2021 4:41 PM, Masahiro Yamada wrote:
> When CONFIG_TRIM_UNUSED_KSYMS is enabled, I see some warnings like this:
>
> nm: arch/x86/entry/vdso/vdso32/note.o: no symbols
>
> $NM (both GNU nm and llvm-nm) warns when no symbol is found in the
> object. Suppress the stderr.
>
> Fixes: bbda5ec671d3 ("kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS")
> Signed-off-by: Masahiro Yamada <[email protected]>

Reviewed-by: Nathan Chancellor <[email protected]>

> ---
>
> scripts/gen_ksymdeps.sh | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/gen_ksymdeps.sh b/scripts/gen_ksymdeps.sh
> index 1324986e1362..5493124e8ee6 100755
> --- a/scripts/gen_ksymdeps.sh
> +++ b/scripts/gen_ksymdeps.sh
> @@ -4,7 +4,10 @@
> set -e
>
> # List of exported symbols
> -ksyms=$($NM $1 | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
> +#
> +# If the object has no symbol, $NM warns 'no symbols'.
> +# Suppress the stdout.
> +ksyms=$($NM $1 2>/dev/null | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
>
> if [ -z "$ksyms" ]; then
> exit 0
>

2021-08-15 03:20:19

by Fangrui Song

Subject: Re: [PATCH] kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y

On Sat, Aug 14, 2021 at 6:15 PM Nathan Chancellor <[email protected]> wrote:
>
> On 8/14/2021 4:41 PM, Masahiro Yamada wrote:
> > When CONFIG_TRIM_UNUSED_KSYMS is enabled, I see some warnings like this:
> >
> > nm: arch/x86/entry/vdso/vdso32/note.o: no symbols
> >
> > $NM (both GNU nm and llvm-nm) warns when no symbol is found in the
> > object. Suppress the stderr.
> >
> > Fixes: bbda5ec671d3 ("kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS")
> > Signed-off-by: Masahiro Yamada <[email protected]>

LGTM.

FWIW binutils>=2.37 `nm -q` can be used to suppress "no symbols"
https://sourceware.org/bugzilla/show_bug.cgi?id=27408

llvm-nm>=13.0.0 supports -q as well.

> Reviewed-by: Nathan Chancellor <[email protected]>
>
> > ---
> >
> > scripts/gen_ksymdeps.sh | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/scripts/gen_ksymdeps.sh b/scripts/gen_ksymdeps.sh
> > index 1324986e1362..5493124e8ee6 100755
> > --- a/scripts/gen_ksymdeps.sh
> > +++ b/scripts/gen_ksymdeps.sh
> > @@ -4,7 +4,10 @@
> > set -e
> >
> > # List of exported symbols
> > -ksyms=$($NM $1 | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
> > +#
> > +# If the object has no symbol, $NM warns 'no symbols'.
> > +# Suppress the stdout.
> > +ksyms=$($NM $1 2>/dev/null | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
> >
> > if [ -z "$ksyms" ]; then
> > exit 0
> >
>
> --
> You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/3afe5054-8129-fe42-b5a4-00bd091b1a0c%40kernel.org.



--
宋方睿

2021-08-15 03:39:06

by Nicolas Pitre

Subject: Re: [PATCH] kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y

On Sun, 15 Aug 2021, Masahiro Yamada wrote:

> When CONFIG_TRIM_UNUSED_KSYMS is enabled, I see some warnings like this:
>
> nm: arch/x86/entry/vdso/vdso32/note.o: no symbols
>
> $NM (both GNU nm and llvm-nm) warns when no symbol is found in the
> object. Suppress the stderr.
>
> Fixes: bbda5ec671d3 ("kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS")
> Signed-off-by: Masahiro Yamada <[email protected]>
> ---
>
> scripts/gen_ksymdeps.sh | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/gen_ksymdeps.sh b/scripts/gen_ksymdeps.sh
> index 1324986e1362..5493124e8ee6 100755
> --- a/scripts/gen_ksymdeps.sh
> +++ b/scripts/gen_ksymdeps.sh
> @@ -4,7 +4,10 @@
> set -e
>
> # List of exported symbols
> -ksyms=$($NM $1 | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
> +#
> +# If the object has no symbol, $NM warns 'no symbols'.
> +# Suppress the stdout.
> +ksyms=$($NM $1 2>/dev/null | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)

You mean stderr.


Nicolas

2021-08-18 04:32:05

by Masahiro Yamada

Subject: Re: [PATCH] kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y

On Sun, Aug 15, 2021 at 12:37 PM Nicolas Pitre <[email protected]> wrote:
>
> On Sun, 15 Aug 2021, Masahiro Yamada wrote:
>
> > When CONFIG_TRIM_UNUSED_KSYMS is enabled, I see some warnings like this:
> >
> > nm: arch/x86/entry/vdso/vdso32/note.o: no symbols
> >
> > $NM (both GNU nm and llvm-nm) warns when no symbol is found in the
> > object. Suppress the stderr.
> >
> > Fixes: bbda5ec671d3 ("kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS")
> > Signed-off-by: Masahiro Yamada <[email protected]>
> > ---
> >
> > scripts/gen_ksymdeps.sh | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/scripts/gen_ksymdeps.sh b/scripts/gen_ksymdeps.sh
> > index 1324986e1362..5493124e8ee6 100755
> > --- a/scripts/gen_ksymdeps.sh
> > +++ b/scripts/gen_ksymdeps.sh
> > @@ -4,7 +4,10 @@
> > set -e
> >
> > # List of exported symbols
> > -ksyms=$($NM $1 | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
> > +#
> > +# If the object has no symbol, $NM warns 'no symbols'.
> > +# Suppress the stdout.
> > +ksyms=$($NM $1 2>/dev/null | sed -n 's/.*__ksym_marker_\(.*\)/\1/p' | tr A-Z a-z)
>
> You mean stderr.


My bad - I will fix it in v2.
Thanks.


--
Best Regards
Masahiro Yamada

2021-08-18 04:32:18

by Masahiro Yamada

Subject: Re: [PATCH] kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y

On Sun, Aug 15, 2021 at 12:18 PM Fāng-ruì Sòng <[email protected]> wrote:
>
> On Sat, Aug 14, 2021 at 6:15 PM Nathan Chancellor <[email protected]> wrote:
> >
> > On 8/14/2021 4:41 PM, Masahiro Yamada wrote:
> > > When CONFIG_TRIM_UNUSED_KSYMS is enabled, I see some warnings like this:
> > >
> > > nm: arch/x86/entry/vdso/vdso32/note.o: no symbols
> > >
> > > $NM (both GNU nm and llvm-nm) warns when no symbol is found in the
> > > object. Suppress the stderr.
> > >
> > > Fixes: bbda5ec671d3 ("kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS")
> > > Signed-off-by: Masahiro Yamada <[email protected]>
>
> LGTM.
>
> FWIW binutils>=2.37 `nm -q` can be used to suppress "no symbols"
> https://sourceware.org/bugzilla/show_bug.cgi?id=27408
>
> llvm-nm>=13.0.0 supports -q as well.


Thanks for the info.
Perhaps, I can note the future migration to -q
in a comment.






--
Best Regards
Masahiro Yamada