Re: [PATCH 1/2] nova-core: Add a library for bitfields in Rust structs

["Alexandre Courbot" <acourbot@nvidia.com>]

On Sat Sep 6, 2025 at 6:29 AM JST, John Hubbard wrote:
> On 9/4/25 4:06 AM, Alexandre Courbot wrote:
>> On Thu Sep 4, 2025 at 4:16 PM JST, Danilo Krummrich wrote:
>>> On Thu Sep 4, 2025 at 5:16 AM CEST, Alexandre Courbot wrote:
>>>> On Thu Sep 4, 2025 at 12:15 AM JST, Joel Fernandes wrote:
>>>> <snip>
>>> 	pub struct PageTableEntry {
>>> 	    63:63     nx          as bool,
>>> 	    62:52     available2  as u16,
>>> 	    51:12     pfn         as u64,
>>> 	    11:9      available   as u8,
>>> 	    1:1       writable    as bool,
>>> 	    0:0       present     as bool,
>>> 	}
>>>
>>> This is also what would be my preferred style for the kernel in general.
>> 
>> Sorry for the confusion. The discussion was whether to keep using the
>> `H:L` syntax of the current macro, or use Rust's inclusive ranges syntax
>> (i.e. `L..=H`), as the `genmask_*` macros currently do.
>> 
>
> The H:L (for example "11:9 available as u8", above) is elegant and readable.
>
> The Rust native syntax "L..=H", much less so.
>
> For this part of the kernel, dealing specifically with bits, feel pretty
> strongly that we should go with "H:L".

We discussed that bit during the Rust DRM meeting, and the consensus was
indeed to go with `H:L` for these macros as this is the syntax typically
used in fields definitions.