Don't combine '-r' and '--export-dynamic' linker options
Checks
Commit Message
Running ld with '-r' switches the linker to a very special mode where
some other linker options don't make sense.
In particular, '--export-dynamic' normally requires that all global
symbols be included in the dynamic symbol table, but a .o file doesn't
even have a dynamic symbol table.
When given both options it looks like the gnu linker just ignores
'--export-dynamic'.
Unfortunately some versions of lld (https://lld.llvm.org/) have a bug
that causes it to try to create a dynamic symbol table in the output
.o file and ends up corrupting it
(https://bugs.llvm.org/show_bug.cgi?id=43552). Current (git) version
of lld now issues an error.
This patch drops $(LDFLAGS) when using -r. With this patch I can build
dpdk with lld.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
---
mk/internal/rte.compile-pre.mk | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Comments
Hi Thomas,
Are you the right maintainer fer reviewing this patch?
Thanks,
Rafael
Rafael Ávila de Espíndola <espindola@scylladb.com> writes:
> Running ld with '-r' switches the linker to a very special mode where
> some other linker options don't make sense.
>
> In particular, '--export-dynamic' normally requires that all global
> symbols be included in the dynamic symbol table, but a .o file doesn't
> even have a dynamic symbol table.
>
> When given both options it looks like the gnu linker just ignores
> '--export-dynamic'.
>
> Unfortunately some versions of lld (https://lld.llvm.org/) have a bug
> that causes it to try to create a dynamic symbol table in the output
> .o file and ends up corrupting it
> (https://bugs.llvm.org/show_bug.cgi?id=43552). Current (git) version
> of lld now issues an error.
>
> This patch drops $(LDFLAGS) when using -r. With this patch I can build
> dpdk with lld.
>
> Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
> ---
> mk/internal/rte.compile-pre.mk | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mk/internal/rte.compile-pre.mk b/mk/internal/rte.compile-pre.mk
> index 0cf3791b4..6cd7e559a 100644
> --- a/mk/internal/rte.compile-pre.mk
> +++ b/mk/internal/rte.compile-pre.mk
> @@ -61,7 +61,7 @@ CHECK_EXPERIMENTAL = $(EXPERIMENTAL_CHECK) $(SRCDIR)/$(EXPORT_MAP) $@
>
> PMDINFO_GEN = $(RTE_SDK_BIN)/app/dpdk-pmdinfogen $@ $@.pmd.c
> PMDINFO_CC = $(CC) $(CPPFLAGS) $(CFLAGS) $(EXTRA_CFLAGS) -c -o $@.pmd.o $@.pmd.c
> -PMDINFO_LD = $(CROSS)ld $(LDFLAGS) -r -o $@.o $@.pmd.o $@
> +PMDINFO_LD = $(CROSS)ld -r -o $@.o $@.pmd.o $@
> PMDINFO_TO_O = if grep -q 'RTE_PMD_REGISTER_.*(.*)' $<; then \
> echo "$(if $V,$(PMDINFO_GEN), PMDINFO $@.pmd.c)" && \
> $(PMDINFO_GEN) && \
> --
> 2.21.0
25/10/2019 03:20, Rafael Ávila de Espíndola:
> Running ld with '-r' switches the linker to a very special mode where
> some other linker options don't make sense.
>
> In particular, '--export-dynamic' normally requires that all global
> symbols be included in the dynamic symbol table, but a .o file doesn't
> even have a dynamic symbol table.
>
> When given both options it looks like the gnu linker just ignores
> '--export-dynamic'.
>
> Unfortunately some versions of lld (https://lld.llvm.org/) have a bug
> that causes it to try to create a dynamic symbol table in the output
> .o file and ends up corrupting it
> (https://bugs.llvm.org/show_bug.cgi?id=43552). Current (git) version
> of lld now issues an error.
>
> This patch drops $(LDFLAGS) when using -r. With this patch I can build
> dpdk with lld.
[...]
> -PMDINFO_LD = $(CROSS)ld $(LDFLAGS) -r -o $@.o $@.pmd.o $@
> +PMDINFO_LD = $(CROSS)ld -r -o $@.o $@.pmd.o $@
Dealing with compiler bugs is really annoying.
I'm afraid removing LDFLAGS may break in some environments.
Could you just filter-out some incompatible options?
And what about meson? Is there some similar issue?
Thomas Monjalon <thomas@monjalon.net> writes:
> 25/10/2019 03:20, Rafael Ávila de Espíndola:
>> Running ld with '-r' switches the linker to a very special mode where
>> some other linker options don't make sense.
>>
>> In particular, '--export-dynamic' normally requires that all global
>> symbols be included in the dynamic symbol table, but a .o file doesn't
>> even have a dynamic symbol table.
>>
>> When given both options it looks like the gnu linker just ignores
>> '--export-dynamic'.
>>
>> Unfortunately some versions of lld (https://lld.llvm.org/) have a bug
>> that causes it to try to create a dynamic symbol table in the output
>> .o file and ends up corrupting it
>> (https://bugs.llvm.org/show_bug.cgi?id=43552). Current (git) version
>> of lld now issues an error.
>>
>> This patch drops $(LDFLAGS) when using -r. With this patch I can build
>> dpdk with lld.
> [...]
>> -PMDINFO_LD = $(CROSS)ld $(LDFLAGS) -r -o $@.o $@.pmd.o $@
>> +PMDINFO_LD = $(CROSS)ld -r -o $@.o $@.pmd.o $@
>
> Dealing with compiler bugs is really annoying.
> I'm afraid removing LDFLAGS may break in some environments.
> Could you just filter-out some incompatible options?
Sure, that works. I will send a v2.
> And what about meson? Is there some similar issue?
As far as I can tell meson produces a .a file instead. In the
build.ninja file I see
build drivers/librte_pmd_dpaa_event.a: STATIC_LINKER drivers/a715181@@rte_pmd_dpaa_event@sta/meson-generated_.._rte_pmd_dpaa_event.pmd.c.o drivers/a715181@@tmp_rte_pmd_dpaa_event@sta/event_dpaa_dpaa_eventdev.c.o
and
rule STATIC_LINKER
command = rm -f $out && gcc-ar $LINK_ARGS $out $in
Cheers,
Rafael
On 12/12/2019 16:05, Thomas Monjalon wrote:
> 25/10/2019 03:20, Rafael Ávila de Espíndola:
>> Running ld with '-r' switches the linker to a very special mode where
>> some other linker options don't make sense.
>>
>> In particular, '--export-dynamic' normally requires that all global
>> symbols be included in the dynamic symbol table, but a .o file doesn't
>> even have a dynamic symbol table.
>>
>> When given both options it looks like the gnu linker just ignores
>> '--export-dynamic'.
>>
>> Unfortunately some versions of lld (https://lld.llvm.org/) have a bug
>> that causes it to try to create a dynamic symbol table in the output
>> .o file and ends up corrupting it
>> (https://bugs.llvm.org/show_bug.cgi?id=43552). Current (git) version
>> of lld now issues an error.
>>
>> This patch drops $(LDFLAGS) when using -r. With this patch I can build
>> dpdk with lld.
> [...]
>> -PMDINFO_LD = $(CROSS)ld $(LDFLAGS) -r -o $@.o $@.pmd.o $@
>> +PMDINFO_LD = $(CROSS)ld -r -o $@.o $@.pmd.o $@
>
> Dealing with compiler bugs is really annoying.
> I'm afraid removing LDFLAGS may break in some environments.
> Could you just filter-out some incompatible options?
Right, detect that LLD is the linker and change LDFLAGS accordingly.
Painful, but the right approach.
>
> And what about meson? Is there some similar issue?
>
>
>
@@ -61,7 +61,7 @@ CHECK_EXPERIMENTAL = $(EXPERIMENTAL_CHECK) $(SRCDIR)/$(EXPORT_MAP) $@
PMDINFO_GEN = $(RTE_SDK_BIN)/app/dpdk-pmdinfogen $@ $@.pmd.c
PMDINFO_CC = $(CC) $(CPPFLAGS) $(CFLAGS) $(EXTRA_CFLAGS) -c -o $@.pmd.o $@.pmd.c
-PMDINFO_LD = $(CROSS)ld $(LDFLAGS) -r -o $@.o $@.pmd.o $@
+PMDINFO_LD = $(CROSS)ld -r -o $@.o $@.pmd.o $@
PMDINFO_TO_O = if grep -q 'RTE_PMD_REGISTER_.*(.*)' $<; then \
echo "$(if $V,$(PMDINFO_GEN), PMDINFO $@.pmd.c)" && \
$(PMDINFO_GEN) && \