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

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Mon, 2026-03-09 at 14:01 -0400, Bruce Ashfield wrote:
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> On Mon, Mar 9, 2026 at 12:54 PM Harish Sadineni
> <Harish.Sadineni@windriver.com> wrote:
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> > On 3/9/2026 9:59 PM, Bruce Ashfield wrote:
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> > >    
> > > CAUTION: This email comes from a non Wind River email account!
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> > > sender and know the content is safe.
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> > > On Mon, Mar 9, 2026 at 12:10 PM Harish Sadineni
> > > <Harish.Sadineni@windriver.com> wrote:
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> > > > 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 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 | 3 +++
> > > > > >  1 file changed, 3 insertions(+)
> > > > > > 
> > > > > > diff --git a/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > b/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > index 4d0a726bb6..b7961bbcdf 100644
> > > > > > --- a/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > +++ b/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > @@ -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.
> > > >  
> > > > 
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> > >  
> > >  
> > > I'm curious about that. Can you share the details ? (diff and the
> > > bitbake error)
> > >  
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> > >  
> >  
> >  As discussed previously, I attempted to use the following in
> > meta/recipes-kernel/linux/linux-yocto_6.18.bb:
> >  
> >  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 ?

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