Re: [dpdk-dev] [PATCH v1] examples/vhost: fix ioat dependency issue

[David Marchand <david.marchand@redhat.com>]

On Wed, Nov 11, 2020 at 12:29 PM Cheng Jiang <Cheng1.jiang@intel.com> wrote:
>
> Fix vhost-switch compiling issue when ioat dependency is missing.
> Change 'RTE_x86' check into 'RTE_RAW_IOAT' check in meson build file
> and update Makefile.

Still failing for me.
98b4c65506 - (HEAD) examples/vhost: fix ioat dependency issue (28
seconds ago) <Cheng Jiang>
a8adac0bc0 - (origin/main) doc: add instructions for building 32-bit
DPDK (5 days ago) <Bruce Richardson>

Please try the reproducer I gave:

rm -f build/vhost-switch build/vhost-switch-static build/vhost-switch-shared
test -d build && rmdir -p build || true
cc -O3 -I/home/dmarchan/dpdk/installdir/usr/local/include -include
rte_config.h -march=native -I/usr/usr/include
-DALLOW_EXPERIMENTAL_API main.c virtio_net.c -o
build/vhost-switch-shared -pthread -Wl,--as-needed
-L/home/dmarchan/dpdk/installdir/usr/local/lib64 -lrte_node
-lrte_graph -lrte_bpf -lrte_flow_classify -lrte_pipeline -lrte_table
-lrte_port -lrte_fib -lrte_ipsec -lrte_vhost -lrte_stack
-lrte_security -lrte_sched -lrte_reorder -lrte_rib -lrte_regexdev
-lrte_rawdev -lrte_pdump -lrte_power -lrte_member -lrte_lpm
-lrte_latencystats -lrte_kni -lrte_jobstats -lrte_ip_frag -lrte_gso
-lrte_gro -lrte_eventdev -lrte_efd -lrte_distributor -lrte_cryptodev
-lrte_compressdev -lrte_cfgfile -lrte_bitratestats -lrte_bbdev
-lrte_acl -lrte_timer -lrte_hash -lrte_metrics -lrte_cmdline -lrte_pci
-lrte_ethdev -lrte_meter -lrte_net -lrte_mbuf -lrte_mempool -lrte_rcu
-lrte_ring -lrte_eal -lrte_telemetry -lrte_kvargs -lbsd
/usr/bin/ld: /tmp/ccqE1W9S.o: in function `new_device':
main.c:(.text+0x173): undefined reference to `ioat_transfer_data_cb'
/usr/bin/ld: main.c:(.text+0x178): undefined reference to
`ioat_check_completed_copies_cb'
/usr/bin/ld: /tmp/ccqE1W9S.o: in function `main':
main.c:(.text.startup+0x25e): undefined reference to `open_ioat'
collect2: error: ld returned 1 exit status
make: *** [Makefile:39: build/vhost-switch-shared] Error 1


There are at least two problems:
- the code in main.c unconditionally expects the ioat stuff to be
available (this is why the link fails above),
- the Makefile unconditionally compiles ioat.c, which you fixed with this patch,

There is a potential additional problem:
I would expect a need for linking against the rte_raw_ioat driver, but
we are "lucky" that all that is used in this example are inlines.
So I guess it works without adding anything to LDFLAGS_SHARED.


>
> Signed-off-by: Cheng Jiang <Cheng1.jiang@intel.com>
> ---
>  examples/vhost/Makefile    | 5 +++++
>  examples/vhost/ioat.h      | 2 +-
>  examples/vhost/meson.build | 2 +-
>  3 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/examples/vhost/Makefile b/examples/vhost/Makefile
> index cec59d0e0f..505e443217 100644
> --- a/examples/vhost/Makefile
> +++ b/examples/vhost/Makefile
> @@ -5,7 +5,12 @@
>  APP = vhost-switch
>
>  # all source are stored in SRCS-y
> +IOAT_PATH = $(shell pkg-config --cflags-only-I libdpdk | sed -e "s/^..//")/rte_ioat_rawdev.h
> +ifeq ($(IOAT_PATH), $(wildcard $(IOAT_PATH)))
> +SRCS-y := main.c virtio_net.c ioat.c
> +else
>  SRCS-y := main.c virtio_net.c
> +endif

I'd rather rely on the driver define since the C code relies on it:
Something like:

 PC_FILE := $(shell $(PKGCONF) --path libdpdk 2>/dev/null)
 CFLAGS += -O3 $(shell $(PKGCONF) --cflags libdpdk)
 LDFLAGS_SHARED = $(shell $(PKGCONF) --libs libdpdk)
 LDFLAGS_STATIC = $(shell $(PKGCONF) --static --libs libdpdk)
+
+HAS_RAW_IOAT=$(shell echo RTE_RAW_IOAT | $(CPP) $(CFLAGS) -P - | tail -1)
+ifeq ($(HAS_RAW_IOAT), 1)
+SRCS-y += ioat.c
+endif


>
>  # Build using pkg-config variables if possible
>  ifneq ($(shell pkg-config --exists libdpdk && echo 0),0)
> diff --git a/examples/vhost/ioat.h b/examples/vhost/ioat.h
> index 9664fcc3ac..d6d0f7c18a 100644
> --- a/examples/vhost/ioat.h
> +++ b/examples/vhost/ioat.h
> @@ -24,7 +24,7 @@ struct dma_for_vhost {
>         uint16_t nr;
>  };
>
> -#ifdef RTE_ARCH_X86
> +#ifdef RTE_RAW_IOAT
>  int open_ioat(const char *value);

main.c should check for RTE_RAW_IOAT before including ioat.h.
And then in this header, you can remove this stub too.


>  #else
>  static int open_ioat(const char *value __rte_unused)


-- 
David Marchand