> -----Original Message----- > From: Jerin Jacob <[email protected]> > Sent: Thursday, September 16, 2021 11:43 AM > To: David Christensen <[email protected]> > Cc: Bruce Richardson <[email protected]>; dpdk-dev > <[email protected]>; Luca Boccassi <[email protected]>; David Marchand > <[email protected]>; [email protected]; Ilya Maximets > <[email protected]>; [email protected]; Ruifeng Wang > <[email protected]>; Honnappa Nagarahalli > <[email protected]>; Ananyev, Konstantin > <[email protected]>; Ferruh Yigit <[email protected]> > Subject: Re: [dpdk-dev] [RFC PATCH] build/pkg-config: remove machine arch > flag > > On Thu, Sep 16, 2021 at 2:53 AM David Christensen <[email protected]> > wrote: > > > > > > > > On 9/15/21 9:28 AM, Bruce Richardson wrote: > > > On Fri, Dec 11, 2020 at 03:51:11PM +0000, Bruce Richardson wrote: > > >> Traditionally any apps built using DPDK had to support the same > > >> instruction sets as supported when the DPDK SDK itself was built, > > >> since that was "leaked" through to the end-app and DPDK headers via > > >> RTE_MACHINE_CPUFLAG_* values. Therefore, when converting over to > > >> meson for app build correctness the "-march=" flag was included in > > >> the pkg-config cflags output. > > >> > > >> However, since the DPDK-specific CPU flags are now obsolete, and we > > >> instead check directly for compiler-defined flags, we should no > > >> longer need to force the exact same architecture match in all > > >> cases. To faciliate such flexibility, a new pkg_config_machine_args > > >> array - which defaults to the existing machine_args array has been > > >> defined. The individual architectures - x86, arm and ppc - can > > >> choose if and how to override this value themselves. > > >> > > >> For x86, since SSE4.2 is the minimum instruction-set level needed > > >> to run DPDK, and since some header files assume that minimum level > > >> of instruction set support, we override the "-march=" value with "- > msse4" > > >> for the pkg-config file. This allows end applications to set their > > >> own "march" value while still ensuring valid DPDK compilation. > > >> > > >> Signed-off-by: Bruce Richardson <[email protected]> > > >> --- > > >> > > >> CC: Jerin Jacob <[email protected]> > > >> CC: Ruifeng Wang <[email protected]> > > >> CC: Honnappa Nagarahalli <[email protected]> > > >> CC: David Christensen <[email protected]> for Feedback > > >> requested from ARM and PPC maintainers as to this change and what > > >> flags, if any, need to be in the .pc file for DPDK on such > > >> platforms. For example - is setting 'pkg_config_machine_args' to > > >> 'machine_args' by default necessary behaviour? > > >> > > > > > > Ping for further thoughts or input on this patch. > > Armv8 has dedicated config(taken least cpu flags which supports all > armv8) for this purpose config/arm/arm64_armv8_linux_gcc. > So this change looks good to me. @Ruifeng Wang (Arm Technology China) > Any comments? >
Agree. For distro build, only armv8-a is requested. The change looks fine. Thanks, Ruifeng > > > > > On initial inspection I don't see any additional value for PPC systems. > > Selection of a CPU through -mcpu implies a full ISA for that CPU, > > including things like vector extensions, at least with respect to the > > minimum supported POWER8 CPU (ISA 2.07) and later ISAs. The values of > > machine_args and pkg_config_machine_args should be identical in all > > cases I can think of. > > > > If a third party OpenPOWER CPU comes along some time in the future > > then the requirements may change. > > > > > > > > Dave
