Re: [dpdk-dev] [EXT] Re: [PATCH] config/arm: add ability to express arch extensions

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

<snip>

> 
> >> >>
> >> >> >
> >> >> > The patch still holds true for CRC though as it is listed
> >> >> > separately below
> >> >> > https://urldefense.proofpoint.com/v2/url?u=https-
> >> >3A__developer.arm.com_architectures_cpu-2Darchitecture_a-
> >> >2D&d=DwIFAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=E3SgYMjtKCMVsB-
> >> >fmvgGV3o-
> >>
> >>g_fjLhk5Pupi9ijohpc&m=i3kC8htMiHjXMoJWUn6QlDVZQCblbFrIJyMc
> >W
> >>
> >>d9nAmM&s=fA4SM6O3iC2HXIK1qSbOHzxVeHoYqcfUebEOwioHC7c&e
> >=
> >> >> > profile/exploration-tools/feature-names-for-a-profile
> >> >CRC is mandatory starting in V8.1, refer to Arm-ARM document.
> >> >
> >> >> >
> >> >> > Also, looks like sve2 support in n2 core might be optional as
> >> >> > per
> >> >above doc?
> >> >> I need to check on this. Some of the info here might not be public
> >yet.
> >> >I found [1]. SVE2 is mandatory feature.
> >> >
> >>
> >> I see thanks for the info I will remove extension from cnxk.
> >>
> >> Do you think the extension infra is still useful for other cases? i.e.
> >older cores
> >> or cases where vendor wants to enable some extensions by default?
> >>
> >> I found a document[1] which describes about extensions not enabled
> >by
> >> default but supported by a given march.
> >> In case of n2 I think memory tagging is one such feature
> >I think the reference is providing a different information than what
> >you are trying to achieve here.
> >
> >It looks like you are trying to address a use case where in the same
> >CPU IP has different features enabled/disabled on different SoCs.
> >This is a valid use case from crypto perspective (due to export control
> >reasons) where-in 2 different SoCs might have crypto enabled/disabled.
> >I am not sure if other features can be enabled/disabled. But, Crypto
> >feature is a good enough reason to address such a use case.
> 
> Yes, that's my intension apologies if the commit log doesn't clarify it properly.
> 
> >
> >IMO,  we should capture the SoC specific details in SoC specific files,
> >in this case in 'arm64_cn10k_linux_gcc'. I believe there were some
> >challenges in doing this.
> 
> Since, all the flags are populated through soc_* variable and
> arm64_cn10k_linux_gcc also translates to soc_cn10k I believe the extensions
> should be reported through
> soc_* variables.
IMO, there will be more SoCs in the future. I prefer to not grow meson.build. 
> 
> Also, do you think +crypto needs to be removed from default n2 config as its
> optional?
Agree. Better to move it to SoC specific configuration.

> 
> >Juraj, do you remember the exact issue?
> >
> >>
> >> [1]https://urldefense.proofpoint.com/v2/url?u=https-
> >3A__developer.arm.com_tools-2Dand-2Dsoftware_open-2Dsource-
> >2D&d=DwIFAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=E3SgYMjtKCMVsB-
> >fmvgGV3o-g_fjLhk5Pupi9ijohpc&m=0oZnXDnO-
> >oYL9lESEaZt_nH_kK8Nc3m0tvdEPpKeFZc&s=WxrPoWhkM2QIFGEKezPK
> >D9oEn7nGFvvgS2ul9ZYx-Kg&e=
> >> software/developer-tools/gnu-toolchain/architecture-support
> >>
> >>
> >> >[1] https://urldefense.proofpoint.com/v2/url?u=https-
> >> >3A__developer.arm.com_ip-
> >> >2Dproducts_processors_neoverse_neoverse-
> >>
> >>2Dn2&d=DwIFAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=E3SgYMjtKCMVsB
> >-
> >> >fmvgGV3o-
> >>
> >>g_fjLhk5Pupi9ijohpc&m=i3kC8htMiHjXMoJWUn6QlDVZQCblbFrIJyMc
> >W
> >> >d9nAmM&s=kP_X-Co0cl4pZ64BZqy5rAFUlkMZE-
> >3EhTVBabm3SW8&e=
> >> >
> >> ><snip>