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 <bruce.richardson@intel.com> --- CC: Jerin Jacob <jerinj@marvell.com> CC: Ruifeng Wang <ruifeng.wang@arm.com> CC: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> CC: David Christensen <drc@linux.vnet.ibm.com> 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? --- buildtools/pkg-config/meson.build | 2 +- config/meson.build | 1 + config/x86/meson.build | 3 +++ 3 files changed, 5 insertions(+), 1 deletion(-) diff --git a/buildtools/pkg-config/meson.build b/buildtools/pkg-config/meson.build index 5f1930428..8e2e24681 100644 --- a/buildtools/pkg-config/meson.build +++ b/buildtools/pkg-config/meson.build @@ -2,7 +2,7 @@ # Copyright(c) 2020 Intel Corporation pkg = import('pkgconfig') -pkg_extra_cflags = ['-include', 'rte_config.h'] + machine_args +pkg_extra_cflags = ['-include', 'rte_config.h'] + pkg_config_machine_args if is_freebsd pkg_extra_cflags += ['-D__BSD_VISIBLE'] endif diff --git a/config/meson.build b/config/meson.build index 3ddcc3539..d58ff781d 100644 --- a/config/meson.build +++ b/config/meson.build @@ -100,6 +100,7 @@ if host_machine.cpu_family().startswith('ppc') else machine_args += '-march=' + machine endif +pkg_config_machine_args = machine_args # may be overriden late per arch toolchain = cc.get_id() dpdk_conf.set_quoted('RTE_TOOLCHAIN', toolchain) diff --git a/config/x86/meson.build b/config/x86/meson.build index 31bfa63b1..fcd75502e 100644 --- a/config/x86/meson.build +++ b/config/x86/meson.build @@ -16,6 +16,9 @@ if cc.get_define('__SSE4_2__', args: machine_args) == '' machine_args += '-msse4' endif +# require SSE4.2 in pkg-config file - don't use -march +pkg_config_machine_args = ['-msse4'] + base_flags = ['SSE', 'SSE2', 'SSE3','SSSE3', 'SSE4_1', 'SSE4_2'] foreach f:base_flags compile_time_cpuflags += ['RTE_CPUFLAG_' + f] -- 2.27.0
On 12/11/20 7:51 AM, 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 <bruce.richardson@intel.com>
> ---
>
> CC: Jerin Jacob <jerinj@marvell.com>
> CC: Ruifeng Wang <ruifeng.wang@arm.com>
> CC: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> CC: David Christensen <drc@linux.vnet.ibm.com>
> 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?
Support for Altivec would be the equivalent here for PPC and I'm not
aware of any additional flags required for supported POWER CPUs on DPDK.
I can't speak to P10 requirements yet but the proposed change is a
don't care for me.
Dave
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 <bruce.richardson@intel.com> > --- > > CC: Jerin Jacob <jerinj@marvell.com> > CC: Ruifeng Wang <ruifeng.wang@arm.com> > CC: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > CC: David Christensen <drc@linux.vnet.ibm.com> > 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. /Bruce > --- > buildtools/pkg-config/meson.build | 2 +- > config/meson.build | 1 + > config/x86/meson.build | 3 +++ > 3 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/buildtools/pkg-config/meson.build b/buildtools/pkg-config/meson.build > index 5f1930428..8e2e24681 100644 > --- a/buildtools/pkg-config/meson.build > +++ b/buildtools/pkg-config/meson.build > @@ -2,7 +2,7 @@ > # Copyright(c) 2020 Intel Corporation > > pkg = import('pkgconfig') > -pkg_extra_cflags = ['-include', 'rte_config.h'] + machine_args > +pkg_extra_cflags = ['-include', 'rte_config.h'] + pkg_config_machine_args > if is_freebsd > pkg_extra_cflags += ['-D__BSD_VISIBLE'] > endif > diff --git a/config/meson.build b/config/meson.build > index 3ddcc3539..d58ff781d 100644 > --- a/config/meson.build > +++ b/config/meson.build > @@ -100,6 +100,7 @@ if host_machine.cpu_family().startswith('ppc') > else > machine_args += '-march=' + machine > endif > +pkg_config_machine_args = machine_args # may be overriden late per arch > > toolchain = cc.get_id() > dpdk_conf.set_quoted('RTE_TOOLCHAIN', toolchain) > diff --git a/config/x86/meson.build b/config/x86/meson.build > index 31bfa63b1..fcd75502e 100644 > --- a/config/x86/meson.build > +++ b/config/x86/meson.build > @@ -16,6 +16,9 @@ if cc.get_define('__SSE4_2__', args: machine_args) == '' > machine_args += '-msse4' > endif > > +# require SSE4.2 in pkg-config file - don't use -march > +pkg_config_machine_args = ['-msse4'] > + > base_flags = ['SSE', 'SSE2', 'SSE3','SSSE3', 'SSE4_1', 'SSE4_2'] > foreach f:base_flags > compile_time_cpuflags += ['RTE_CPUFLAG_' + f] > -- > 2.27.0 >
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 <bruce.richardson@intel.com>
>> ---
>>
>> CC: Jerin Jacob <jerinj@marvell.com>
>> CC: Ruifeng Wang <ruifeng.wang@arm.com>
>> CC: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
>> CC: David Christensen <drc@linux.vnet.ibm.com> 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.
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
On Thu, Sep 16, 2021 at 2:53 AM David Christensen <drc@linux.vnet.ibm.com> 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 <bruce.richardson@intel.com> > >> --- > >> > >> CC: Jerin Jacob <jerinj@marvell.com> > >> CC: Ruifeng Wang <ruifeng.wang@arm.com> > >> CC: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > >> CC: David Christensen <drc@linux.vnet.ibm.com> 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? > > 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
> -----Original Message----- > From: Jerin Jacob <jerinjacobk@gmail.com> > Sent: Thursday, September 16, 2021 11:43 AM > To: David Christensen <drc@linux.vnet.ibm.com> > Cc: Bruce Richardson <bruce.richardson@intel.com>; dpdk-dev > <dev@dpdk.org>; Luca Boccassi <bluca@debian.org>; David Marchand > <david.marchand@redhat.com>; ian.stokes@intel.com; Ilya Maximets > <i.maximets@ovn.org>; jerinj@marvell.com; Ruifeng Wang > <Ruifeng.Wang@arm.com>; Honnappa Nagarahalli > <Honnappa.Nagarahalli@arm.com>; Ananyev, Konstantin > <konstantin.ananyev@intel.com>; Ferruh Yigit <ferruh.yigit@intel.com> > Subject: Re: [dpdk-dev] [RFC PATCH] build/pkg-config: remove machine arch > flag > > On Thu, Sep 16, 2021 at 2:53 AM David Christensen <drc@linux.vnet.ibm.com> > 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 <bruce.richardson@intel.com> > > >> --- > > >> > > >> CC: Jerin Jacob <jerinj@marvell.com> > > >> CC: Ruifeng Wang <ruifeng.wang@arm.com> > > >> CC: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > > >> CC: David Christensen <drc@linux.vnet.ibm.com> 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
> -----Original Message----- > From: dev <dev-bounces@dpdk.org> On Behalf Of Ruifeng Wang > Sent: Thursday, September 16, 2021 6:17 PM > To: Jerin Jacob <jerinjacobk@gmail.com>; David Christensen > <drc@linux.vnet.ibm.com> > Cc: Bruce Richardson <bruce.richardson@intel.com>; dpdk-dev > <dev@dpdk.org>; Luca Boccassi <bluca@debian.org>; David Marchand > <david.marchand@redhat.com>; ian.stokes@intel.com; Ilya Maximets > <i.maximets@ovn.org>; jerinj@marvell.com; Honnappa Nagarahalli > <Honnappa.Nagarahalli@arm.com>; Ananyev, Konstantin > <konstantin.ananyev@intel.com>; Ferruh Yigit <ferruh.yigit@intel.com>; nd > <nd@arm.com> > Subject: Re: [dpdk-dev] [RFC PATCH] build/pkg-config: remove machine arch > flag > > > -----Original Message----- > > From: Jerin Jacob <jerinjacobk@gmail.com> > > Sent: Thursday, September 16, 2021 11:43 AM > > To: David Christensen <drc@linux.vnet.ibm.com> > > Cc: Bruce Richardson <bruce.richardson@intel.com>; dpdk-dev > > <dev@dpdk.org>; Luca Boccassi <bluca@debian.org>; David Marchand > > <david.marchand@redhat.com>; ian.stokes@intel.com; Ilya Maximets > > <i.maximets@ovn.org>; jerinj@marvell.com; Ruifeng Wang > > <Ruifeng.Wang@arm.com>; Honnappa Nagarahalli > > <Honnappa.Nagarahalli@arm.com>; Ananyev, Konstantin > > <konstantin.ananyev@intel.com>; Ferruh Yigit <ferruh.yigit@intel.com> > > Subject: Re: [dpdk-dev] [RFC PATCH] build/pkg-config: remove machine > > arch flag > > > > On Thu, Sep 16, 2021 at 2:53 AM David Christensen > > <drc@linux.vnet.ibm.com> > > 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 <bruce.richardson@intel.com> > > > >> --- > > > >> > > > >> CC: Jerin Jacob <jerinj@marvell.com> > > > >> CC: Ruifeng Wang <ruifeng.wang@arm.com> > > > >> CC: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > > > >> CC: David Christensen <drc@linux.vnet.ibm.com> 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. This is fine if "cross-file" is provided when doing distro build. However, when "-Dmachine=default"/"-Dplatform=default" is used instead of "cross-file" to do distro build, current change in config/meson.build will lead to " pkg_config_machine_args = -march=generic". This is because generic build is handled by subsequent arch specific config on Arm. I think moving the change in config/meson.build down below line #307 subdir(arch_subdir) will address aforementioned issue. As by the time, machine_args has been updated with proper value. > > 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
On Fri, 11 Dec 2020 15:51:11 +0000
Bruce Richardson <bruce.richardson@intel.com> 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 <bruce.richardson@intel.com>
This looks fine, and can see no negatives in the comments.
Could you rebase and resubmit a new version if still relevant?
On Wed, Jun 14, 2023 at 12:33:10PM -0700, Stephen Hemminger wrote:
> On Fri, 11 Dec 2020 15:51:11 +0000
> Bruce Richardson <bruce.richardson@intel.com> 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 <bruce.richardson@intel.com>
>
> This looks fine, and can see no negatives in the comments.
> Could you rebase and resubmit a new version if still relevant?
>
There seemed to be a general lack of interest in it, sadly, so not sure
I'll resubmit.