Re: [PATCH v12.1 1/1] rust: gpu: Add GPU buddy allocator bindings

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

On Tue Mar 17, 2026 at 3:51 AM JST, John Hubbard wrote:
> On 3/16/26 6:12 AM, Alexandre Courbot wrote:
>> On Mon Mar 9, 2026 at 10:53 PM JST, Joel Fernandes wrote:
> ...
>>> +//! // Create a 1GB buddy allocator with 4KB minimum chunk size.
>>> +//! let buddy = GpuBuddy::new(GpuBuddyParams {
>>> +//!     base_offset: 0,
>>> +//!     physical_memory_size: SZ_1G as u64,
>>> +//!     chunk_size: SZ_4K,
>> 
>> `chunk_size` is an interesting case. The C API uses a `u64`, but I think
>> we can reasonably consider that we won't ever need chunks larger than
>> 4GB (or can we :O). I'm actually ok with using a `usize` for this one.
>> 
>> One of the first things the C code does is throwing an error if it is
>> not a power of 2, so maybe we can even request an `Alignment`?
>> 
>> I'm a bit torn as to whether we should use a `u64` to conform with the C
>> API, but doing so would mean we cannot use an `Alignment`...
>
> Alex, have you seen my Alignment patch [1], for that? It's sitting 
> around with only Miguel having responded, but seems like exactly
> what you're talking about here.

Not exactly - this patch provides a shortcut for creating an Alignment
from a u64, but it doesn't allow to store alignments larger than 4GB on
a 32-bit architecture since the value itself is still stored as a `usize`.

But that's really a theoretical worry of mine anyway - nobody will ever
work with buffers larger than 4GB on a 32-bit arch to begin with.