[EXT] Re: [PATCH 1/1] build: update link args and includes for libarchive

[Srikanth Yalavarthi]

> -----Original Message-----
> From: Bruce Richardson <bruce.richardson at intel.com>
> Sent: 23 October 2023 14:56
> To: Srikanth Yalavarthi <syalavarthi at marvell.com>
> Cc: Aaron Conole <aconole at redhat.com>; Igor Russkikh
> <irusskikh at marvell.com>; David Marchand <david.marchand at redhat.com>;
> dev at dpdk.org; Shivah Shankar Shankar Narayan Rao
> <sshankarnara at marvell.com>; Jerin Jacob Kollanukkaran
> <jerinj at marvell.com>; stable at dpdk.org
> Subject: [EXT] Re: [PATCH 1/1] build: update link args and includes for
> libarchive
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Fri, Oct 20, 2023 at 10:01:35AM -0700, Srikanth Yalavarthi wrote:
> > In order to avoid linking with all libraries listed as Libs.private in
> > libarchive.pc, libarchive is not added to ext_deps during meson setup.
> >
> > Since libarchive is not added to ext_deps, cross-compilation or native
> > compilation with libarchive installed in non-standard location fails
> > with errors related to "cannot find -larchive"
> > or "archive.h: No such file or directory". In order to fix the build
> > failures, user is required to define the 'c_args' and 'c_link_args'
> > with '-I<includedir>' and '-L<libdir>'.
> >
> > This patch updates meson build files to add libarchive's includedir
> > and libdir to compiler flags and would not require setting c_args and
> > c_link_args externally.
> >
> > Fixes: 40edb9c0d36b ("eal: handle compressed firmware")
> > Cc: stable at dpdk.org
> >
> > Signed-off-by: Srikanth Yalavarthi <syalavarthi at marvell.com>
> > ---
> 
> Checking back through the mail archives I'm still a little unclear as to what
> breaks when we try using libarchive as any other package with a pkg-config
> file? I would have thought the best solution was just to add libarchive as an
> external dependency, found using pkg-config, to EAL. When we add it as a
> dependency, rather than using c/ldflags, we should get all this path fixup for
> free?
> Can you clarify what breaks when we add libarchive as a libeal dependency
> only?

Below is my observation.

In current implementation, we are looking for libarchive's availability through pkg-config.
When found, we are setting RTE_HAS_LIBARCHIVE=1 and adding '-larchive' to ldflags.

Since, we are not adding libarchive to ext_deps (to avoid linking with deps.private), the
variables provided by pkg-config like 'includedir' and 'libdir' are ignored by meson and
are not used as part of c_args (-I<includedir>) and c_link_args (-L<libdir>).

In this case, build would fail during cross-compilation and native  compilation (when
libarchive is not installed through package managers like yum/apt). And, we need to
manually set c_args and c_link_args as per the build environment to fix the failures.

This patch fixes the issue observed and avoids the requirement to set c_args and c_link_args
manually . Below are the steps to reproduce the issue (cross-compile for aarch64). Tested on
ubuntu:20.04 docker. Same can be reproduced for native build, if libarchive is not installed
through apt-get.


rm -rf /dpdk-buildtest && mkdir -p /dpdk-buildtest

# libarchive
cd /dpdk-buildtest
wget -N https://www.libarchive.org/downloads/libarchive-3.6.1.tar.gz
tar -xzf libarchive-3.6.1.tar.gz
cd libarchive-3.6.1
./configure --prefix /dpdk-buildtest/install-aarch64 --host=aarch64-linux-gnu --without-xml2 --without-lzma --without-zlib
make
make install

# dpdk
cd /dpdk-buildtest
git clone https://dpdk.org/git/dpdk
cd dpdk
git checkout main
export PKG_CONFIG_PATH=/dpdk-buildtest/install-aarch64/lib/pkgconfig
meson setup --prefix /dpdk-buildtest/install-aarch64 --cross-file config/arm/arm64_armv8_linux_gcc build
ninja -C build

### meson log ### libarchive is found by pkg-config
Has header "execinfo.h" : YES
Found pkg-config: /usr/bin/aarch64-linux-gnu-pkg-config (0.29.1)
Run-time dependency libarchive found: YES 3.6.1
Run-time dependency libbsd found: NO (tried pkgconfig)
Run-time dependency jansson found: NO (tried pkgconfig)


### compilation log ### -I<inlcudedir> is not used
[39/2835] Compiling C object 'lib/76b5a35@@rte_eal at sta/eal_unix_eal_firmware.c.o'.
FAILED: lib/76b5a35@@rte_eal at sta/eal_unix_eal_firmware.c.o
aarch64-linux-gnu-gcc -Ilib/76b5a35@@rte_eal at sta -Ilib -I../lib -I. -I../ -Iconfig -I../config -Ilib/eal/include -I../lib/eal/include -Ilib/eal/linux/include -I../lib/eal/linux/include -Ilib/eal/arm/include -I../lib/eal/arm/include -Ilib/eal/common -I../lib/eal/common -Ilib/eal -I../lib/eal -Ilib/kvargs -I../lib/kvargs -Ilib/log -I../lib/log -Ilib/telemetry/../metrics -I../lib/telemetry/../metrics -Ilib/telemetry -I../lib/telemetry -fdiagnostics-color=always -pipe -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Wextra -std=c11 -O3 -include rte_config.h -Wcast-qual -Wdeprecated -Wformat -Wformat-nonliteral -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wpointer-arith -Wsign-compare -Wstrict-prototypes -Wundef -Wwrite-strings -Wno-address-of-packed-member -Wno-packed-not-aligned -Wno-missing-field-initializers -D_GNU_SOURCE -fPIC -march=armv8-a+crc -moutline-atomics -DALLOW_EXPERIMENTAL_API -DALLOW_INTERNAL_API -Wno-format-truncation '-DABI_VERSION="24.0"' -DRTE_LOG_DEFAULT_LOGTYPE=lib.eal -MD -MQ 'lib/76b5a35@@rte_eal at sta/eal_unix_eal_firmware.c.o' -MF 'lib/76b5a35@@rte_eal at sta/eal_unix_eal_firmware.c.o.d' -o 'lib/76b5a35@@rte_eal at sta/eal_unix_eal_firmware.c.o' -c ../lib/eal/unix/eal_firmware.c
../lib/eal/unix/eal_firmware.c:6:10: fatal error: archive.h: No such file or directory
    6 | #include <archive.h>
      |          ^~~~~~~~~~~
compilation terminated.

> 
> /Bruce