rust: Enable the new_uninit feature for kernel and driver crates

  The unstable new_uninit feature enables various library APIs to create
uninitialized containers, such as `Box::assume_init()`. This is
necessary to build abstractions that directly initialize memory at the
target location, instead of doing copies through the stack.

Will be used by the DRM scheduler abstraction in the kernel crate, and
by field-wise initialization (e.g. using `place!()` or a future
replacement macro which may itself live in `kernel`) in driver crates.

See [1] [2] [3] for background information.

[1] https://github.com/Rust-for-Linux/linux/issues/879
[2] https://github.com/Rust-for-Linux/linux/issues/2
[3] https://github.com/rust-lang/rust/issues/63291

Signed-off-by: Asahi Lina <lina@asahilina.net>
---
 rust/kernel/lib.rs     | 1 +
 scripts/Makefile.build | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)


---
base-commit: 83f978b63fa7ad474ca22d7e2772c5988101c9bd
change-id: 20230224-rust-new_uninit-a575d34987c3

Thank you,
~~ Lina
  

On Fri, Feb 24, 2023 at 05:09:47PM +0900, Asahi Lina wrote:
> The unstable new_uninit feature enables various library APIs to create
> uninitialized containers, such as `Box::assume_init()`. This is
> necessary to build abstractions that directly initialize memory at the
> target location, instead of doing copies through the stack.
> 
> Will be used by the DRM scheduler abstraction in the kernel crate, and
> by field-wise initialization (e.g. using `place!()` or a future
> replacement macro which may itself live in `kernel`) in driver crates.

Very useful to me as some constructors in the USB bindings that I'm
writting might make use of unitialized memory.

Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
  

On Fri, 24 Feb 2023 17:09:47 +0900
Asahi Lina <lina@asahilina.net> wrote:

> The unstable new_uninit feature enables various library APIs to create
> uninitialized containers, such as `Box::assume_init()`. This is
> necessary to build abstractions that directly initialize memory at the
> target location, instead of doing copies through the stack.
> 
> Will be used by the DRM scheduler abstraction in the kernel crate, and
> by field-wise initialization (e.g. using `place!()` or a future
> replacement macro which may itself live in `kernel`) in driver crates.
> 
> See [1] [2] [3] for background information.
> 
> [1] https://github.com/Rust-for-Linux/linux/issues/879
> [2] https://github.com/Rust-for-Linux/linux/issues/2
> [3] https://github.com/rust-lang/rust/issues/63291
> 
> Signed-off-by: Asahi Lina <lina@asahilina.net>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/lib.rs     | 1 +
>  scripts/Makefile.build | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index 223564f9f0cc..1118cd3e0b5f 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -17,6 +17,7 @@
>  #![feature(core_ffi_c)]
>  #![feature(dispatch_from_dyn)]
>  #![feature(generic_associated_types)]
> +#![feature(new_uninit)]
>  #![feature(receiver_trait)]
>  #![feature(unsize)]
>  
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index a0d5c6cca76d..0f637e1ca8dc 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
>  # Compile Rust sources (.rs)
>  # ---------------------------------------------------------------------------
>  
> -rust_allowed_features := core_ffi_c
> +rust_allowed_features := core_ffi_c,new_uninit
>  
>  rust_common_cmd = \
>  	RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \
> 
> ---
> base-commit: 83f978b63fa7ad474ca22d7e2772c5988101c9bd
> change-id: 20230224-rust-new_uninit-a575d34987c3
> 
> Thank you,
> ~~ Lina
>
  

Asahi Lina <lina@asahilina.net> writes:

> The unstable new_uninit feature enables various library APIs to create
> uninitialized containers, such as `Box::assume_init()`. This is
> necessary to build abstractions that directly initialize memory at the
> target location, instead of doing copies through the stack.
>
> Will be used by the DRM scheduler abstraction in the kernel crate, and
> by field-wise initialization (e.g. using `place!()` or a future
> replacement macro which may itself live in `kernel`) in driver crates.
>
> See [1] [2] [3] for background information.
>
> [1] https://github.com/Rust-for-Linux/linux/issues/879
> [2] https://github.com/Rust-for-Linux/linux/issues/2
> [3] https://github.com/rust-lang/rust/issues/63291
>
> Signed-off-by: Asahi Lina <lina@asahilina.net>
> ---
>  rust/kernel/lib.rs     | 1 +
>  scripts/Makefile.build | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index 223564f9f0cc..1118cd3e0b5f 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -17,6 +17,7 @@
>  #![feature(core_ffi_c)]
>  #![feature(dispatch_from_dyn)]
>  #![feature(generic_associated_types)]
> +#![feature(new_uninit)]
>  #![feature(receiver_trait)]
>  #![feature(unsize)]
>  
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index a0d5c6cca76d..0f637e1ca8dc 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
>  # Compile Rust sources (.rs)
>  # ---------------------------------------------------------------------------
>  
> -rust_allowed_features := core_ffi_c
> +rust_allowed_features := core_ffi_c,new_uninit

What is the purpose of adding the feature here? The kernel crate seems
to compile fine without this.

BR Andreas
  

On 27/02/2023 22.09, Andreas Hindborg wrote:
> 
> Asahi Lina <lina@asahilina.net> writes:
> 
>> The unstable new_uninit feature enables various library APIs to create
>> uninitialized containers, such as `Box::assume_init()`. This is
>> necessary to build abstractions that directly initialize memory at the
>> target location, instead of doing copies through the stack.
>>
>> Will be used by the DRM scheduler abstraction in the kernel crate, and
>> by field-wise initialization (e.g. using `place!()` or a future
>> replacement macro which may itself live in `kernel`) in driver crates.
>>
>> See [1] [2] [3] for background information.
>>
>> [1] https://github.com/Rust-for-Linux/linux/issues/879
>> [2] https://github.com/Rust-for-Linux/linux/issues/2
>> [3] https://github.com/rust-lang/rust/issues/63291
>>
>> Signed-off-by: Asahi Lina <lina@asahilina.net>
>> ---
>>  rust/kernel/lib.rs     | 1 +
>>  scripts/Makefile.build | 2 +-
>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
>> index 223564f9f0cc..1118cd3e0b5f 100644
>> --- a/rust/kernel/lib.rs
>> +++ b/rust/kernel/lib.rs
>> @@ -17,6 +17,7 @@
>>  #![feature(core_ffi_c)]
>>  #![feature(dispatch_from_dyn)]
>>  #![feature(generic_associated_types)]
>> +#![feature(new_uninit)]
>>  #![feature(receiver_trait)]
>>  #![feature(unsize)]
>>  
>> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
>> index a0d5c6cca76d..0f637e1ca8dc 100644
>> --- a/scripts/Makefile.build
>> +++ b/scripts/Makefile.build
>> @@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
>>  # Compile Rust sources (.rs)
>>  # ---------------------------------------------------------------------------
>>  
>> -rust_allowed_features := core_ffi_c
>> +rust_allowed_features := core_ffi_c,new_uninit
> 
> What is the purpose of adding the feature here? The kernel crate seems
> to compile fine without this.

It's for the upcoming DRM abstractions, as I mentioned in the commit
message. There's so many dependencies that I'm trying to get as much as
I can early to avoid having to review very big patchsets down the line ^^

~~ Lina
  

On Mon, Feb 27, 2023 at 2:15 PM Andreas Hindborg <nmi@metaspace.dk> wrote:
>
> What is the purpose of adding the feature here? The kernel crate seems
> to compile fine without this.

`rust_allowed_features` is the list of features that crates outside
`rust/` can use (e.g. drivers).

The goal is to control which unstable features are used outside the
`kernel` crate and to avoid mistakenly relying on them.

Cheers,
Miguel
  

Asahi Lina <lina@asahilina.net> writes:

> On 27/02/2023 22.09, Andreas Hindborg wrote:
>> 
>> Asahi Lina <lina@asahilina.net> writes:
>> 
>>> The unstable new_uninit feature enables various library APIs to create
>>> uninitialized containers, such as `Box::assume_init()`. This is
>>> necessary to build abstractions that directly initialize memory at the
>>> target location, instead of doing copies through the stack.
>>>
>>> Will be used by the DRM scheduler abstraction in the kernel crate, and
>>> by field-wise initialization (e.g. using `place!()` or a future
>>> replacement macro which may itself live in `kernel`) in driver crates.
>>>
>>> See [1] [2] [3] for background information.
>>>
>>> [1] https://github.com/Rust-for-Linux/linux/issues/879
>>> [2] https://github.com/Rust-for-Linux/linux/issues/2
>>> [3] https://github.com/rust-lang/rust/issues/63291
>>>
>>> Signed-off-by: Asahi Lina <lina@asahilina.net>
>>> ---
>>>  rust/kernel/lib.rs     | 1 +
>>>  scripts/Makefile.build | 2 +-
>>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
>>> index 223564f9f0cc..1118cd3e0b5f 100644
>>> --- a/rust/kernel/lib.rs
>>> +++ b/rust/kernel/lib.rs
>>> @@ -17,6 +17,7 @@
>>>  #![feature(core_ffi_c)]
>>>  #![feature(dispatch_from_dyn)]
>>>  #![feature(generic_associated_types)]
>>> +#![feature(new_uninit)]
>>>  #![feature(receiver_trait)]
>>>  #![feature(unsize)]
>>>  
>>> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
>>> index a0d5c6cca76d..0f637e1ca8dc 100644
>>> --- a/scripts/Makefile.build
>>> +++ b/scripts/Makefile.build
>>> @@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
>>>  # Compile Rust sources (.rs)
>>>  # ---------------------------------------------------------------------------
>>>  
>>> -rust_allowed_features := core_ffi_c
>>> +rust_allowed_features := core_ffi_c,new_uninit
>> 
>> What is the purpose of adding the feature here? The kernel crate seems
>> to compile fine without this.
>
> It's for the upcoming DRM abstractions, as I mentioned in the commit
> message. There's so many dependencies that I'm trying to get as much as
> I can early to avoid having to review very big patchsets down the line ^^

I got confused on the different makefile rules used to build kernel
crate vs module crates. Looks good 👍

Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
  

> The unstable new_uninit feature enables various library APIs to create
> uninitialized containers, such as `Box::assume_init()`. This is
> necessary to build abstractions that directly initialize memory at the
> target location, instead of doing copies through the stack.
>
> Will be used by the DRM scheduler abstraction in the kernel crate, and
> by field-wise initialization (e.g. using `place!()` or a future
> replacement macro which may itself live in `kernel`) in driver crates.
>
> See [1] [2] [3] for background information.
>
> [1] https://github.com/Rust-for-Linux/linux/issues/879
> [2] https://github.com/Rust-for-Linux/linux/issues/2
> [3] https://github.com/rust-lang/rust/issues/63291
>
> Signed-off-by: Asahi Lina <lina@asahilina.net>
> ---

Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
  

On Fri, Feb 24, 2023 at 9:10 AM Asahi Lina <lina@asahilina.net> wrote:
>
> The unstable new_uninit feature enables various library APIs to create
> uninitialized containers, such as `Box::assume_init()`. This is
> necessary to build abstractions that directly initialize memory at the
> target location, instead of doing copies through the stack.
>
> Will be used by the DRM scheduler abstraction in the kernel crate, and
> by field-wise initialization (e.g. using `place!()` or a future
> replacement macro which may itself live in `kernel`) in driver crates.
>
> See [1] [2] [3] for background information.
>
> [1] https://github.com/Rust-for-Linux/linux/issues/879
> [2] https://github.com/Rust-for-Linux/linux/issues/2
> [3] https://github.com/rust-lang/rust/issues/63291

Applied to `rust-next` (reworded to use `Link` tags). Thanks!

Cheers,
Miguel