From: "Danilo Krummrich" <dakr@kernel.org>
To: "John Hubbard" <jhubbard@nvidia.com>
Cc: "Alexandre Courbot" <acourbot@nvidia.com>,
"Joel Fernandes" <joelagnelf@nvidia.com>,
"Timur Tabi" <ttabi@nvidia.com>,
"Alistair Popple" <apopple@nvidia.com>,
"Eliot Courtney" <ecourtney@nvidia.com>,
"Shashank Sharma" <shashanks@nvidia.com>,
"Zhi Wang" <zhiw@nvidia.com>, "David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Miguel Ojeda" <ojeda@kernel.org>,
"Alex Gaynor" <alex.gaynor@gmail.com>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Benno Lossin" <lossin@kernel.org>,
"Andreas Hindborg" <a.hindborg@kernel.org>,
"Alice Ryhl" <aliceryhl@google.com>,
"Trevor Gross" <tmgross@umich.edu>,
rust-for-linux@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] rust: sizes: add u64 variants of SZ_* constants
Date: Tue, 10 Mar 2026 17:59:36 +0100 [thread overview]
Message-ID: <DGZ9GMLXYZZ5.17CYRGI7NXGC7@kernel.org> (raw)
In-Reply-To: <20260310023145.120037-2-jhubbard@nvidia.com>
On Tue Mar 10, 2026 at 3:31 AM CET, John Hubbard wrote:
> Drivers that operate on 64-bit address spaces (GPU framebuffer layouts,
> DMA regions, etc.) frequently need these size constants as a u64 type.
> Today this requires repeated usize-to-u64 conversion calls like
> usize_as_u64(SZ_1M) or u64::from_safe_cast(SZ_1M), which adds
> boilerplate without any safety benefit.
>
> Add u64-typed constants (SZ_1K_U64 through SZ_2G_U64) alongside the
> existing usize constants. Every value fits in u64 (actually, within a
> u32 for that matter), so the as-cast is always lossless.
>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Feel free to add:
Suggested-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/all/DGB9G697GSWO.3VBFGU5MKFPMR@kernel.org/
Link: https://lore.kernel.org/all/DGHI8WRKBQS9.38910L6FIIZTE@kernel.org/
As mentioned in the other thread, we could also make this GPU infrastructure and
have GPU specific usize / isize types.
next prev parent reply other threads:[~2026-03-10 16:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-10 2:31 [PATCH 0/2] rust, nova-core: use u64 variants of SZ_* constants John Hubbard
2026-03-10 2:31 ` [PATCH 1/2] rust: sizes: add " John Hubbard
2026-03-10 13:51 ` Miguel Ojeda
2026-03-10 16:42 ` Daniel Almeida
2026-03-10 16:53 ` Danilo Krummrich
2026-03-10 20:20 ` Miguel Ojeda
2026-03-10 20:47 ` Danilo Krummrich
2026-03-10 20:55 ` Danilo Krummrich
2026-03-10 22:08 ` Miguel Ojeda
2026-03-10 22:13 ` John Hubbard
2026-03-10 22:19 ` John Hubbard
2026-03-11 8:01 ` Alexandre Courbot
2026-03-12 0:21 ` John Hubbard
2026-03-10 16:59 ` Danilo Krummrich [this message]
2026-03-10 2:31 ` [PATCH 2/2] gpu: nova-core: use SZ_*_U64 constants from kernel::sizes John Hubbard
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