Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Jerin Jacob Kollanukkaran]

> -----Original Message-----
> From: Yongseok Koh <yskoh@mellanox.com>
> Sent: Friday, May 3, 2019 5:58 PM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; thomas@monjalon.net
> Cc: dev@dpdk.org; bruce.richardson@intel.com; Pavan Nikhilesh Bhagavatula
> <pbhagavatula@marvell.com>; shahafs@mellanox.com; gavin.hu@arm.com;
> Honnappa.Nagarahalli@arm.com; stable@dpdk.org
> Subject: [EXT] [PATCH v2] build: disable armv8 crypto extension
> > Per armv8 crypto extension support, make build always enable it by default as
> long as compiler supports the feature while meson build only enables it for
> 'default' machine of generic armv8 architecture.
> 
> It is known that not all the armv8 platforms have the crypto extension. For
> example, Mellanox BlueField has a variant which doesn't have it. If crypto
> enabled binary runs on such a platform, rte_eal_init() fails.
> 
> '+crypto' flag currently implies only '+aes' and '+sha2' and enabling it will
> generate the crypto instructions only when crypto intrinsics are used.
> For the devices supporting 8.2 crypto or newer, compiler could generate such
> instructions beyond intrinsics or asm code. For example, compiler can generate
> 3-way exclusive OR instructions if sha3 is supported. However, it has to be
> enabled by adding '+sha3' as of today.
> 
> In DPDK, armv8 cryptodev is the only one which requires the crypto support.
> As it even uses external library of Marvell which is compiled out of DPDK with
> crypto support and there's run-time check for required cpuflags, crypto support
> can be disabled in DPDK.
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> ---

Acked-by: Jerin Jacob <jerinj@marvell.com>

[dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Yongseok Koh]

Per armv8 crypto extension support, make build always enable it by default
as long as compiler supports the feature while meson build only enables it
for 'default' machine of generic armv8 architecture.

It is known that not all the armv8 platforms have the crypto extension. For
example, Mellanox BlueField has a variant which doesn't have it. If crypto
enabled binary runs on such a platform, rte_eal_init() fails.

'+crypto' flag currently implies only '+aes' and '+sha2' and enabling it
will generate the crypto instructions only when crypto intrinsics are used.
For the devices supporting 8.2 crypto or newer, compiler could generate
such instructions beyond intrinsics or asm code. For example, compiler can
generate 3-way exclusive OR instructions if sha3 is supported. However, it
has to be enabled by adding '+sha3' as of today.

In DPDK, armv8 cryptodev is the only one which requires the crypto support.
As it even uses external library of Marvell which is compiled out of DPDK
with crypto support and there's run-time check for required cpuflags,
crypto support can be disabled in DPDK.

Cc: stable@dpdk.org

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
---

v2:
* disable crypto support instead of having a build config

 config/arm/meson.build        | 2 +-
 mk/machine/armv8a/rte.vars.mk | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/config/arm/meson.build b/config/arm/meson.build
index 7fa6ed3105..abc8cf346c 100644
--- a/config/arm/meson.build
+++ b/config/arm/meson.build
@@ -74,7 +74,7 @@ flags_octeontx2_extra = [
 	['RTE_USE_C11_MEM_MODEL', true]]
 
 machine_args_generic = [
-	['default', ['-march=armv8-a+crc+crypto']],
+	['default', ['-march=armv8-a+crc']],
 	['native', ['-march=native']],
 	['0xd03', ['-mcpu=cortex-a53']],
 	['0xd04', ['-mcpu=cortex-a35']],
diff --git a/mk/machine/armv8a/rte.vars.mk b/mk/machine/armv8a/rte.vars.mk
index 8252efbb7b..5e3ffc3adf 100644
--- a/mk/machine/armv8a/rte.vars.mk
+++ b/mk/machine/armv8a/rte.vars.mk
@@ -28,4 +28,4 @@
 # CPU_LDFLAGS =
 # CPU_ASFLAGS =
 
-MACHINE_CFLAGS += -march=armv8-a+crc+crypto
+MACHINE_CFLAGS += -march=armv8-a+crc
-- 
2.11.0

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Honnappa Nagarahalli]

Hi Yongseok,
	We need to enable 'CONFIG_RTE_LIBRTE_PMD_ARMV8_CRYPTO' (which would require a documentation change in [1]). I think this change might have an impact on the existing users. Does this change need to be documented somewhere (at least in the release notes)?

[1] https://doc.dpdk.org/guides-19.02/cryptodevs/armv8.html

> -----Original Message-----
> From: Yongseok Koh <yskoh@mellanox.com>
> Sent: Friday, May 3, 2019 7:28 AM
> To: jerinj@marvell.com; thomas@monjalon.net
> Cc: dev@dpdk.org; bruce.richardson@intel.com; pbhagavatula@marvell.com;
> shahafs@mellanox.com; Gavin Hu (Arm Technology China)
> <Gavin.Hu@arm.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com>; stable@dpdk.org
> Subject: [PATCH v2] build: disable armv8 crypto extension
> 
> Per armv8 crypto extension support, make build always enable it by default
> as long as compiler supports the feature while meson build only enables it for
> 'default' machine of generic armv8 architecture.
> 
> It is known that not all the armv8 platforms have the crypto extension. For
> example, Mellanox BlueField has a variant which doesn't have it. If crypto
> enabled binary runs on such a platform, rte_eal_init() fails.
> 
> '+crypto' flag currently implies only '+aes' and '+sha2' and enabling it will
> generate the crypto instructions only when crypto intrinsics are used.
> For the devices supporting 8.2 crypto or newer, compiler could generate such
> instructions beyond intrinsics or asm code. For example, compiler can
> generate 3-way exclusive OR instructions if sha3 is supported. However, it
> has to be enabled by adding '+sha3' as of today.
> 
> In DPDK, armv8 cryptodev is the only one which requires the crypto support.
> As it even uses external library of Marvell which is compiled out of DPDK with
> crypto support and there's run-time check for required cpuflags, crypto
> support can be disabled in DPDK.
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> ---
> 
> v2:
> * disable crypto support instead of having a build config
> 
>  config/arm/meson.build        | 2 +-
>  mk/machine/armv8a/rte.vars.mk | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/config/arm/meson.build b/config/arm/meson.build index
> 7fa6ed3105..abc8cf346c 100644
> --- a/config/arm/meson.build
> +++ b/config/arm/meson.build
> @@ -74,7 +74,7 @@ flags_octeontx2_extra = [
>  	['RTE_USE_C11_MEM_MODEL', true]]
> 
>  machine_args_generic = [
> -	['default', ['-march=armv8-a+crc+crypto']],
> +	['default', ['-march=armv8-a+crc']],
IIRC, this would impact distro packaging as well. Adding Luca.

>  	['native', ['-march=native']],
>  	['0xd03', ['-mcpu=cortex-a53']],
>  	['0xd04', ['-mcpu=cortex-a35']],
> diff --git a/mk/machine/armv8a/rte.vars.mk
> b/mk/machine/armv8a/rte.vars.mk index 8252efbb7b..5e3ffc3adf 100644
> --- a/mk/machine/armv8a/rte.vars.mk
> +++ b/mk/machine/armv8a/rte.vars.mk
> @@ -28,4 +28,4 @@
>  # CPU_LDFLAGS =
>  # CPU_ASFLAGS =
> 
> -MACHINE_CFLAGS += -march=armv8-a+crc+crypto
> +MACHINE_CFLAGS += -march=armv8-a+crc
> --
> 2.11.0

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Honnappa Nagarahalli]

> 
> Hi Yongseok,
> 	We need to enable 'CONFIG_RTE_LIBRTE_PMD_ARMV8_CRYPTO'
> (which would require a documentation change in [1]).
I enabled this and compiled, the compilation fails. Ideally (as discussed in other threads), the PMD code itself does not make use of the crypto instructions, so we should be able to compile the PMDs. Crypto functionality should not be available only if crypto is not available from the CPU or the crypto library is not present. Otherwise, there is no way to use crypto in distro package without recompiling. We can take this up separately. 

 I think this change might
> have an impact on the existing users. Does this change need to be documented
> somewhere (at least in the release notes)?
> 
> [1] https://doc.dpdk.org/guides-19.02/cryptodevs/armv8.html
> 
> > -----Original Message-----
> > From: Yongseok Koh <yskoh@mellanox.com>
> > Sent: Friday, May 3, 2019 7:28 AM
> > To: jerinj@marvell.com; thomas@monjalon.net
> > Cc: dev@dpdk.org; bruce.richardson@intel.com;
> > pbhagavatula@marvell.com; shahafs@mellanox.com; Gavin Hu (Arm
> > Technology China) <Gavin.Hu@arm.com>; Honnappa Nagarahalli
> > <Honnappa.Nagarahalli@arm.com>; stable@dpdk.org
> > Subject: [PATCH v2] build: disable armv8 crypto extension
> >
> > Per armv8 crypto extension support, make build always enable it by
> > default as long as compiler supports the feature while meson build
> > only enables it for 'default' machine of generic armv8 architecture.
> >
> > It is known that not all the armv8 platforms have the crypto
> > extension. For example, Mellanox BlueField has a variant which doesn't
> > have it. If crypto enabled binary runs on such a platform, rte_eal_init() fails.
> >
> > '+crypto' flag currently implies only '+aes' and '+sha2' and enabling
> > it will generate the crypto instructions only when crypto intrinsics are used.
> > For the devices supporting 8.2 crypto or newer, compiler could
> > generate such instructions beyond intrinsics or asm code. For example,
> > compiler can generate 3-way exclusive OR instructions if sha3 is
> > supported. However, it has to be enabled by adding '+sha3' as of today.
> >
> > In DPDK, armv8 cryptodev is the only one which requires the crypto support.
> > As it even uses external library of Marvell which is compiled out of
> > DPDK with crypto support and there's run-time check for required
> > cpuflags, crypto support can be disabled in DPDK.
> >
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> > ---
> >
> > v2:
> > * disable crypto support instead of having a build config
> >
> >  config/arm/meson.build        | 2 +-
> >  mk/machine/armv8a/rte.vars.mk | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/config/arm/meson.build b/config/arm/meson.build index
> > 7fa6ed3105..abc8cf346c 100644
> > --- a/config/arm/meson.build
> > +++ b/config/arm/meson.build
> > @@ -74,7 +74,7 @@ flags_octeontx2_extra = [
> >  	['RTE_USE_C11_MEM_MODEL', true]]
> >
> >  machine_args_generic = [
> > -	['default', ['-march=armv8-a+crc+crypto']],
> > +	['default', ['-march=armv8-a+crc']],
> IIRC, this would impact distro packaging as well. Adding Luca.
> 
> >  	['native', ['-march=native']],
> >  	['0xd03', ['-mcpu=cortex-a53']],
> >  	['0xd04', ['-mcpu=cortex-a35']],
> > diff --git a/mk/machine/armv8a/rte.vars.mk
> > b/mk/machine/armv8a/rte.vars.mk index 8252efbb7b..5e3ffc3adf 100644
> > --- a/mk/machine/armv8a/rte.vars.mk
> > +++ b/mk/machine/armv8a/rte.vars.mk
> > @@ -28,4 +28,4 @@
> >  # CPU_LDFLAGS =
> >  # CPU_ASFLAGS =
> >
> > -MACHINE_CFLAGS += -march=armv8-a+crc+crypto
> > +MACHINE_CFLAGS += -march=armv8-a+crc
> > --
> > 2.11.0

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Yongseok Koh]

On Fri, May 03, 2019 at 04:10:47PM +0000, Honnappa Nagarahalli wrote:
> > 
> > Hi Yongseok,
> > 	We need to enable 'CONFIG_RTE_LIBRTE_PMD_ARMV8_CRYPTO'
> > (which would require a documentation change in [1]).
> I enabled this and compiled, the compilation fails. Ideally (as discussed in
> other threads), the PMD code itself does not make use of the crypto
> instructions, so we should be able to compile the PMDs. Crypto functionality
> should not be available only if crypto is not available from the CPU or the
> crypto library is not present. Otherwise, there is no way to use crypto in
> distro package without recompiling. We can take this up separately. 

Like you mentioned, the failure isn't due to lack of '+crypto' flag but the
external library.

CONFIG_RTE_LIBRTE_PMD_ARMV8_CRYPTO is disabled by default because it needs the
external library. In order to enable the config, ARMV8_CRYPTO_LIB_PATH must be
specified. Makefile mandates it.

	ifneq ($(MAKECMDGOALS),clean)
	ifneq ($(MAKECMDGOALS),config)
	ifeq ($(ARMV8_CRYPTO_LIB_PATH),)
	$(error "Please define ARMV8_CRYPTO_LIB_PATH environment variable")
	endif
	endif
	endif

armv8 crypto pmd has nothing to do with '+crypto' cpuflag but the external
library (compiled with '+crypto' flag) has to be linked. Without the external
library, it is meaningless to compile the armv8 crypto PMD because we don't have
any fallback.

In runtime, in order to guarantee the final binary runs w/o crash, it checks
cpuflag of the target host with rte_cpu_get_flag_enabled().

>  I think this change might have an impact on the existing users. Does this
>  change need to be documented somewhere (at least in the release notes)?

Practically, there would be no impact. Even if user's app makes use of crypto
instructions, the build config of the app should have the flag.

> > 
> > [1] https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdoc.dpdk.org%2Fguides-19.02%2Fcryptodevs%2Farmv8.html&data=02%7C01%7Cyskoh%40mellanox.com%7C4d6fc9819e4e4a5b1ba508d6cfe1e91d%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636924966530971290&sdata=r3VFKjX44T1g4ORlibYCuCpCDQl1BPQyhzfEe%2BGz%2Fy8%3D&reserved=0
> > 
> > > -----Original Message-----
> > > From: Yongseok Koh <yskoh@mellanox.com>
> > > Sent: Friday, May 3, 2019 7:28 AM
> > > To: jerinj@marvell.com; thomas@monjalon.net
> > > Cc: dev@dpdk.org; bruce.richardson@intel.com;
> > > pbhagavatula@marvell.com; shahafs@mellanox.com; Gavin Hu (Arm
> > > Technology China) <Gavin.Hu@arm.com>; Honnappa Nagarahalli
> > > <Honnappa.Nagarahalli@arm.com>; stable@dpdk.org
> > > Subject: [PATCH v2] build: disable armv8 crypto extension
> > >
> > > Per armv8 crypto extension support, make build always enable it by
> > > default as long as compiler supports the feature while meson build
> > > only enables it for 'default' machine of generic armv8 architecture.
> > >
> > > It is known that not all the armv8 platforms have the crypto
> > > extension. For example, Mellanox BlueField has a variant which doesn't
> > > have it. If crypto enabled binary runs on such a platform, rte_eal_init() fails.
> > >
> > > '+crypto' flag currently implies only '+aes' and '+sha2' and enabling
> > > it will generate the crypto instructions only when crypto intrinsics are used.
> > > For the devices supporting 8.2 crypto or newer, compiler could
> > > generate such instructions beyond intrinsics or asm code. For example,
> > > compiler can generate 3-way exclusive OR instructions if sha3 is
> > > supported. However, it has to be enabled by adding '+sha3' as of today.
> > >
> > > In DPDK, armv8 cryptodev is the only one which requires the crypto support.
> > > As it even uses external library of Marvell which is compiled out of
> > > DPDK with crypto support and there's run-time check for required
> > > cpuflags, crypto support can be disabled in DPDK.
> > >
> > > Cc: stable@dpdk.org
> > >
> > > Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> > > ---
> > >
> > > v2:
> > > * disable crypto support instead of having a build config
> > >
> > >  config/arm/meson.build        | 2 +-
> > >  mk/machine/armv8a/rte.vars.mk | 2 +-
> > >  2 files changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/config/arm/meson.build b/config/arm/meson.build index
> > > 7fa6ed3105..abc8cf346c 100644
> > > --- a/config/arm/meson.build
> > > +++ b/config/arm/meson.build
> > > @@ -74,7 +74,7 @@ flags_octeontx2_extra = [
> > >  	['RTE_USE_C11_MEM_MODEL', true]]
> > >
> > >  machine_args_generic = [
> > > -	['default', ['-march=armv8-a+crc+crypto']],
> > > +	['default', ['-march=armv8-a+crc']],
> > IIRC, this would impact distro packaging as well. Adding Luca.
> > 
> > >  	['native', ['-march=native']],
> > >  	['0xd03', ['-mcpu=cortex-a53']],
> > >  	['0xd04', ['-mcpu=cortex-a35']],
> > > diff --git a/mk/machine/armv8a/rte.vars.mk
> > > b/mk/machine/armv8a/rte.vars.mk index 8252efbb7b..5e3ffc3adf 100644
> > > --- a/mk/machine/armv8a/rte.vars.mk
> > > +++ b/mk/machine/armv8a/rte.vars.mk
> > > @@ -28,4 +28,4 @@
> > >  # CPU_LDFLAGS =
> > >  # CPU_ASFLAGS =
> > >
> > > -MACHINE_CFLAGS += -march=armv8-a+crc+crypto
> > > +MACHINE_CFLAGS += -march=armv8-a+crc
> > > --
> > > 2.11.0
> 

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Yongseok Koh]

> On May 3, 2019, at 10:50 AM, Yongseok Koh <yskoh@mellanox.com> wrote:
> 
>> I think this change might have an impact on the existing users. Does this
>> change need to be documented somewhere (at least in the release notes)?
> 
> Practically, there would be no impact. Even if user's app makes use of crypto
> instructions, the build config of the app should have the flag.

On IRC, I could see you concerned about the case where user app derives build
flags from DPDK like apps under the examples directory. Yes, that's a valid
concern.

Thomas/Jerin, where could be the best spot to document it? Just release note?
I think release note would be fine.

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Jerin Jacob Kollanukkaran]

> -----Original Message-----
> From: Yongseok Koh <yskoh@mellanox.com>
> Sent: Tuesday, May 7, 2019 3:17 AM
> To: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
> Cc: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; Thomas Monjalon
> <thomas@monjalon.net>; dev@dpdk.org; bruce.richardson@intel.com;
> Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>; Shahaf Shuler
> <shahafs@mellanox.com>; Gavin Hu (Arm Technology China)
> <Gavin.Hu@arm.com>; stable@dpdk.org; Luca Boccassi
> <bluca@debian.org>; nd <nd@arm.com>
> Subject: [EXT] Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto
> extension
> 
> > On May 3, 2019, at 10:50 AM, Yongseok Koh <yskoh@mellanox.com>
> wrote:
> >
> >> I think this change might have an impact on the existing users. Does
> >> this change need to be documented somewhere (at least in the release
> notes)?
> >
> > Practically, there would be no impact. Even if user's app makes use of
> > crypto instructions, the build config of the app should have the flag.
> 
> On IRC, I could see you concerned about the case where user app derives
> build flags from DPDK like apps under the examples directory. Yes, that's a
> valid concern.

Is there any DPDK example application would depend on the armv8 crypto flags? IMO, None of
the applications are directly using armv8 crypto instruction. Even such as comes for any external DPDK
app which is not in dpdk.org tree then it can be added in APP makefile.
IMO, app writes should be aware of the need for using +crypto if he/she using the crypto instruction.

> 
> Thomas/Jerin, where could be the best spot to document it? Just release
> note?
> I think release note would be fine.

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Honnappa Nagarahalli]

> > Subject: [EXT] Re: [dpdk-stable] [PATCH v2] build: disable armv8
> > crypto extension
> >
> > > On May 3, 2019, at 10:50 AM, Yongseok Koh <yskoh@mellanox.com>
> > wrote:
> > >
> > >> I think this change might have an impact on the existing users.
> > >> Does this change need to be documented somewhere (at least in the
> > >> release
> > notes)?
> > >
> > > Practically, there would be no impact. Even if user's app makes use
> > > of crypto instructions, the build config of the app should have the flag.
> >
> > On IRC, I could see you concerned about the case where user app
> > derives build flags from DPDK like apps under the examples directory.
> > Yes, that's a valid concern.
> 
> Is there any DPDK example application would depend on the armv8 crypto
> flags? IMO, None of the applications are directly using armv8 crypto
It is not about DPDK's example application. We have control over that.

> instruction. Even such as comes for any external DPDK app which is not in
> dpdk.org tree then it can be added in APP makefile.
> IMO, app writes should be aware of the need for using +crypto if he/she
> using the crypto instruction.
Agree. But, it might be that the app writer might have depended on the +crypto coming from DPDK build system, in which case, she/he needs to know the change through release notes?

I do not think it needs to be documented anywhere else.

> 
> >
> > Thomas/Jerin, where could be the best spot to document it? Just
> > release note?
> > I think release note would be fine.
> 

Re: [dpdk-stable] [PATCH v2] build: disable armv8 crypto extension

[Jerin Jacob Kollanukkaran]

> -----Original Message-----
> From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
> Sent: Tuesday, May 7, 2019 4:34 PM
> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; yskoh@mellanox.com
> Cc: thomas@monjalon.net; dev@dpdk.org; bruce.richardson@intel.com; Pavan
> Nikhilesh Bhagavatula <pbhagavatula@marvell.com>; Shahaf Shuler
> <shahafs@mellanox.com>; Gavin Hu (Arm Technology China)
> <Gavin.Hu@arm.com>; stable@dpdk.org; Luca Boccassi <bluca@debian.org>;
> nd <nd@arm.com>; nd <nd@arm.com>
> Subject: [EXT] RE: [dpdk-stable] [PATCH v2] build: disable armv8 crypto
> extension
> 
> > > Subject: [EXT] Re: [dpdk-stable] [PATCH v2] build: disable armv8
> > > crypto extension
> > >
> > > > On May 3, 2019, at 10:50 AM, Yongseok Koh <yskoh@mellanox.com>
> > > wrote:
> > > >
> > > >> I think this change might have an impact on the existing users.
> > > >> Does this change need to be documented somewhere (at least in the
> > > >> release
> > > notes)?
> > > >
> > > > Practically, there would be no impact. Even if user's app makes
> > > > use of crypto instructions, the build config of the app should have the flag.
> > >
> > > On IRC, I could see you concerned about the case where user app
> > > derives build flags from DPDK like apps under the examples directory.
> > > Yes, that's a valid concern.
> >
> > Is there any DPDK example application would depend on the armv8 crypto
> > flags? IMO, None of the applications are directly using armv8 crypto
> It is not about DPDK's example application. We have control over that.
> 
> > instruction. Even such as comes for any external DPDK app which is not
> > in dpdk.org tree then it can be added in APP makefile.
> > IMO, app writes should be aware of the need for using +crypto if
> > he/she using the crypto instruction.
> Agree. But, it might be that the app writer might have depended on the +crypto
> coming from DPDK build system, in which case, she/he needs to know the
> change through release notes?
> 
> I do not think it needs to be documented anywhere else.

Agree and no harm in updating the release notes.

> 
> >
> > >
> > > Thomas/Jerin, where could be the best spot to document it? Just
> > > release note?
> > > I think release note would be fine.
> >