Hellwig has some excellent points and people are up in arms solely because he’s not giving the green light for the shiny new toy.
Keep the wrappers in your code instead of making life painful for others
This is a perfectly valid approach, anyone claiming he’s resistant for no reason has never tried maintaining a multi language code base.
If you want to use something that’s not C, be that assembly or Rust, you write to C interfaces and deal with the impedance mismatch yourself as far as I’m concerned.
Again an entirely reasonable approach. There is precedence for this approach in the kernel/dma and I see no reason to change this now, unless a full kernel/dma rewrite to Rust were to occur.
What they are asking is not to change the c code to suit rust, but to leave the C code as is, and have a single Rust-written wrapper that links into the C DMA code so that other Rust drivers can link into the wrapper. Additionally, said wrapper is not to be maintained by Hellwig, but by the maintainers of the drivers that will use the wrapper, so without overhead for Hellwig.
He is not asking to not make his work harder, he’s explicitly asking to make it harder to write rust drivers that use DMA.
So you think Hellwig doesn’t understand what is and isn’t intended to go into the kernel/dma that dma maintainers would then be responsible for?
You don’t seem to be familiar with either the full conversation the developers had (its all available) or you don’t understand how the Linux project is structured and maintained.
From the email chain:
On Thu, Jan 16, 2025 at 02:17:24PM +0100, Danilo Krummrich wrote:
Since there hasn’t been a reply so far, I assume that we’re good with
maintaining the DMA Rust abstractions separately.
No, I’m not. This was an explicit:
Nacked-by: Christoph Hellwig
And I also do not want another maintainer. If you want to make Linux impossible to maintain due to a cross-language codebase do that in your driver so that you have to do it instead of spreading this cancer
to core subsystems. (where this cancer explicitly is a cross-languagecodebase and not rust itself, just to escape the flameware brigade).
Hellwig has some excellent points and people are up in arms solely because he’s not giving the green light for the shiny new toy.
This is a perfectly valid approach, anyone claiming he’s resistant for no reason has never tried maintaining a multi language code base.
Again an entirely reasonable approach. There is precedence for this approach in the kernel/dma and I see no reason to change this now, unless a full kernel/dma rewrite to Rust were to occur.
What they are asking is not to change the c code to suit rust, but to leave the C code as is, and have a single Rust-written wrapper that links into the C DMA code so that other Rust drivers can link into the wrapper. Additionally, said wrapper is not to be maintained by Hellwig, but by the maintainers of the drivers that will use the wrapper, so without overhead for Hellwig.
He is not asking to not make his work harder, he’s explicitly asking to make it harder to write rust drivers that use DMA.
So you think Hellwig doesn’t understand what is and isn’t intended to go into the kernel/dma that dma maintainers would then be responsible for?
You don’t seem to be familiar with either the full conversation the developers had (its all available) or you don’t understand how the Linux project is structured and maintained.
From the email chain:
On Thu, Jan 16, 2025 at 02:17:24PM +0100, Danilo Krummrich wrote: