Re: [OE-core] [PATCH v7 01/14] linux-yocto: conditionally add clang/rust/bindgen-cli-native to DEPENDS

[Harish Sadineni <Harish.Sadineni@windriver.com>]

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On 3/10/2026 6:14 PM, Bruce Ashfield wrote:
> **
> *CAUTION: This email comes from a non Wind River email account!*
> Do not click links or open attachments unless you recognize the sender 
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>
> On Tue, Mar 10, 2026 at 6:58 AM Harish Sadineni 
> <Harish.Sadineni@windriver.com> wrote:
>
>
>     On 3/10/2026 12:50 AM, Richard Purdie wrote:
>     > CAUTION: This email comes from a non Wind River email account!
>     > Do not click links or open attachments unless you recognize the
>     sender and know the content is safe.
>     >
>     > On Mon, 2026-03-09 at 14:01 -0400, Bruce Ashfield wrote:
>     >>
>     >>
>     >> On Mon, Mar 9, 2026 at 12:54 PM Harish Sadineni
>     >> <Harish.Sadineni@windriver.com> wrote:
>     >>>
>     >>>
>     >>>
>     >>>
>     >>> On 3/9/2026 9:59 PM, Bruce Ashfield wrote:
>     >>>
>     >>>
>     >>>> CAUTION: This email comes from a non Wind River email account!
>     >>>>   Do not click links or open attachments unless you recognize the
>     >>>> sender and know the content is safe.
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>> On Mon, Mar 9, 2026 at 12:10 PM Harish Sadineni
>     >>>> <Harish.Sadineni@windriver.com> wrote:
>     >>>>
>     >>>>
>     >>>>>
>     >>>>>
>     >>>>>
>     >>>>>
>     >>>>> On 3/9/2026 4:56 PM, Richard Purdie wrote:
>     >>>>>
>     >>>>>
>     >>>>>> CAUTION: This email comes from a non Wind River email
>     >>>>>> account!
>     >>>>>> Do not click links or open attachments unless you recognize
>     >>>>>> the sender and know the content is safe.
>     >>>>>>
>     >>>>>> On Wed, 2026-03-04 at 09:43 -0800, Sadineni, Harish via
>     >>>>>> lists.openembedded.org
>     <https://urldefense.com/v3/__http://lists.openembedded.org__;!!AjveYdw8EvQ!ekkiIdFR1oUUFgkUmXVgRrlc4N10osQLVSoHUP7tqKnyuU2FDh5UdcpyUkPIW6qIyPNmuAqUaeJv3wtCoY4XeJd8am36JgQ$>
>     wrote:
>     >>>>>>
>     >>>>>>> From: Harish Sadineni <Harish.Sadineni@windriver.com>
>     >>>>>>>
>     >>>>>>> Conditionally add 'clang-native', 'rust-native' and
>     >>>>>>> 'bindgen-cli-native' to 'DEPENDS'
>     >>>>>>> when Kernel Rust Support is enabled.
>     >>>>>>>
>     >>>>>>> These tools are required for building Rust-enabled kernels
>     >>>>>>> and for
>     >>>>>>> generating Rust FFI bindings via bindgen during the kernel
>     >>>>>>> build.
>     >>>>>>>
>     >>>>>>> This ensures the additional dependencies are only pulled in
>     >>>>>>> when
>     >>>>>>> Rust support is explicitly enabled, avoiding unnecessary
>     >>>>>>> native
>     >>>>>>> dependencies for non-Rust kernel builds.
>     >>>>>>>
>     >>>>>>> Signed-off-by: Harish Sadineni
>     >>>>>>> <Harish.Sadineni@windriver.com>
>     >>>>>>> ---
>     >>>>>>>   meta/recipes-kernel/linux/linux-yocto.inc
>     <https://urldefense.com/v3/__http://linux-yocto.inc__;!!AjveYdw8EvQ!ekkiIdFR1oUUFgkUmXVgRrlc4N10osQLVSoHUP7tqKnyuU2FDh5UdcpyUkPIW6qIyPNmuAqUaeJv3wtCoY4XeJd8KLPsVX0$>
>     | 3 +++
>     >>>>>>>   1 file changed, 3 insertions(+)
>     >>>>>>>
>     >>>>>>> diff --git a/meta/recipes-kernel/linux/linux-yocto.inc
>     <https://urldefense.com/v3/__http://linux-yocto.inc__;!!AjveYdw8EvQ!ekkiIdFR1oUUFgkUmXVgRrlc4N10osQLVSoHUP7tqKnyuU2FDh5UdcpyUkPIW6qIyPNmuAqUaeJv3wtCoY4XeJd8KLPsVX0$>
>     >>>>>>> b/meta/recipes-kernel/linux/linux-yocto.inc
>     <https://urldefense.com/v3/__http://linux-yocto.inc__;!!AjveYdw8EvQ!ekkiIdFR1oUUFgkUmXVgRrlc4N10osQLVSoHUP7tqKnyuU2FDh5UdcpyUkPIW6qIyPNmuAqUaeJv3wtCoY4XeJd8KLPsVX0$>
>     >>>>>>> index 4d0a726bb6..b7961bbcdf 100644
>     >>>>>>> --- a/meta/recipes-kernel/linux/linux-yocto.inc
>     <https://urldefense.com/v3/__http://linux-yocto.inc__;!!AjveYdw8EvQ!ekkiIdFR1oUUFgkUmXVgRrlc4N10osQLVSoHUP7tqKnyuU2FDh5UdcpyUkPIW6qIyPNmuAqUaeJv3wtCoY4XeJd8KLPsVX0$>
>     >>>>>>> +++ b/meta/recipes-kernel/linux/linux-yocto.inc
>     <https://urldefense.com/v3/__http://linux-yocto.inc__;!!AjveYdw8EvQ!ekkiIdFR1oUUFgkUmXVgRrlc4N10osQLVSoHUP7tqKnyuU2FDh5UdcpyUkPIW6qIyPNmuAqUaeJv3wtCoY4XeJd8KLPsVX0$>
>     >>>>>>> @@ -76,11 +76,14 @@ do_install:append(){
>     >>>>>>>  KERNEL_FEATURES:append:qemuall = " features/kernel-
>     >>>>>>> sample/kernel-sample.scc"
>     >>>>>>>
>     >>>>>>>   KERNEL_DEBUG ?= ""
>     >>>>>>> +KERNEL_RUST_SUPPORT ?= ""
>     >>>>>>>   # These used to be version specific, but are now common
>     >>>>>>> dependencies.  New
>     >>>>>>>   # tools / dependencies will continue to be added in
>     >>>>>>> version specific recipes.
>     >>>>>>>   DEPENDS += '${@bb.utils.contains_any("ARCH", [ "x86",
>     >>>>>>> "arm64", "powerpc" ], "elfutils-native", "", d)}'
>     >>>>>>>   DEPENDS += "openssl-native util-linux-native"
>     >>>>>>>   DEPENDS += "gmp-native libmpc-native"
>     >>>>>>> +RUST_KERNEL_DEPENDS ?=
>     >>>>>>> "${@bb.utils.contains('KERNEL_RUST_SUPPORT', 'True',
>     >>>>>>> 'clang-native rust-native bindgen-cli-native', '', d)}"
>     >>>>>>> +DEPENDS += "${RUST_KERNEL_DEPENDS}"
>     >>>>>>>
>     >>>>>>>   # Some options depend on CONFIG_PAHOLE_VERSION, so need to
>     >>>>>>> make pahole-native available before do_kernel_configme
>     >>>>>>>   do_kernel_configme[depends] +=
>     >>>>>>> '${@bb.utils.contains("KERNEL_DEBUG", "True", "pahole-
>     >>>>>>> native:do_populate_sysroot", "", d)}'
>     >>>>>>>
>     >>>>>> I thought we were going to try and use KERNEL_FEATURES for
>     >>>>>> this?
>     >>>>>>
>     >>>>>   Hi Richard,
>     >>>>>
>     >>>>>   I have tried this but i got circular dependency error with
>     >>>>> KERNEL_FEATURES. So, I opted using variable
>     >>>>> KERNEL_RUST_SUPPORT.
>     >>>>>
>     >>>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>> I'm curious about that. Can you share the details ? (diff and the
>     >>>> bitbake error)
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>>
>     >>>   As discussed previously, I attempted to use the following in
>     >>> meta/recipes-kernel/linux/linux-yocto_6.18.bb
>     <https://urldefense.com/v3/__http://linux-yocto_6.18.bb__;!!AjveYdw8EvQ!ekkiIdFR1oUUFgkUmXVgRrlc4N10osQLVSoHUP7tqKnyuU2FDh5UdcpyUkPIW6qIyPNmuAqUaeJv3wtCoY4XeJd8cBMffSY$>:
>     >>>
>     >>>   KERNEL_FEATURES:append = "
>     ${@bb.utils.contains('KERNEL_FEATURES',
>     >>> 'rust-kernel', ' features/kernel-rust/kernel-rust.scc', '', d)}"
>     >>>
>     >>>   This resulted in a BitBake variable dependency chain
>     failure. The
>     >>> issue occurs because the expression is trying to read
>     >>> KERNEL_FEATURES
>     >>>   while simultaneously modifying KERNEL_FEATURES, which creates a
>     >>> circular dependency.
>     >>>
>     >>
>     >> Yes, that's clearly not going to work, but that wouldn't have been
>     >> the suggestion.
>     >>
>     >> Wasn't Richard asking about setting the RUST_KERNEL_DEPENDS
>     based on
>     >> the KERNEL_FEATURES containing rust.scc ?
>     We understood like Richard suggestion is to use KERNEL_FEATURES
>     everywhere instead of KERNEL_RUST_SUPPORT variable.
>
>     We can use the KERNEL_RUST_SUPPORT variable to append rust.scc to
>     KERNEL_FEATURES and then we could make other checks depends on
>     KERNEL_FEATURES.
>     But as the other recipes (make-mod-scripts, kernel-devsrc,
>     module-rust.bbclass) do not know about KERNEL_FEATURES, so again
>     we've
>     to depend on KERNEL_RUST_SUPPORT Variable.
>
>
> I'm curious as to what you think is different about KERNEL_RUST_SUPPORT
> and KERNEL_FEATURES as variables ?
There is no difference i guess.
>
> They are both defined in the kernel recipe namespace, so any 
> limitations about
> the visibility of one, is true about the other.

We will set KERNEL_RUST_SUPPORT = "true" in local.conf, so it is 
globally visible.
In contrast, KERNEL_FEATURES is conditionally set based on 
KERNEL_RUST_SUPPORT inside the kernel recipe,
meaning its value is only determined at the recipe level and not 
accessible elsewhere.

Thanks,
Harish
>
> or am I missing something ?
>
> Bruce
>
>
>     So, for consistency we used everywhere KERNEL_RUST_SUPPORT.
>
>     Is this implementation ok or we should switch to use -
>     KERNEL_FEATURES in kernel recipes and
>     KERNEL_RUST_SUPPORT in other recipes.
>
>     Thanks,
>     Harish
>     > Yes, along with maybe with a tweak to the KERNEL_FEATURES code which
>     > could expand " rust " or maybe " kernel-rust "in KERNEL_FEATURES
>     into
>     > "features/kernel-rust/kernel-rust.scc" too just so there was a nice
>     > short cut for it?
>     >
>     > Cheers,
>     >
>     > Richard
>     >
>     >
>     >
>
>
>
> -- 
> - Thou shalt not follow the NULL pointer, for chaos and madness await 
> thee at its end
> - "Use the force Harry" - Gandalf, Star Trek II
>

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