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From: "Danilo Krummrich" <dakr@kernel.org>
To: "John Hubbard" <jhubbard@nvidia.com>
Cc: "Alexandre Courbot" <acourbot@nvidia.com>,
	"Alice Ryhl" <aliceryhl@google.com>,
	"David Airlie" <airlied@gmail.com>, "Gary Guo" <gary@garyguo.net>,
	"Simona Vetter" <simona@ffwll.ch>,
	"Alistair Popple" <apopple@nvidia.com>,
	"Timur Tabi" <ttabi@nvidia.com>,
	"Eliot Courtney" <ecourtney@nvidia.com>,
	"Zhi Wang" <zhiw@nvidia.com>, <nova-gpu@lists.linux.dev>,
	<dri-devel@lists.freedesktop.org>,
	<rust-for-linux@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] gpu: nova-core: falcon: use I/O projection to check transfer bounds
Date: Sat, 25 Jul 2026 00:27:35 +0200	[thread overview]
Message-ID: <DK75LUA4NLGI.3P29AIZQE20V2@kernel.org> (raw)
In-Reply-To: <e7ba2c90-6d4f-487e-bd25-56d568ba1f26@nvidia.com>

On Fri Jul 24, 2026 at 8:10 PM CEST, John Hubbard wrote:
> Sort of "conceptually pre-existing" problem, but "handle" doesn't
> quite work as a name, because handles are supposed to be opaque
> items that one just uses to find and refer to things.

This is inherited from the C API where from its perspective the returned base
DMA address of the allocation actually serves as a handle.

In Rust the actual handle is represented by different types with different
invariants and hence capabilties.

(For instance, dma::CoherentBox does not expose the DMA address at all, and
hence provides access to its contents through a direct mutable reference,
whereas dma::CoherentHandle only provides access to the DMA address and does not
have a CPU virtual mapping; dma::Coherent provides access to both.)

Both dma::Coherent and dma::CoherentHandle have a dma_handle() method which
provides access to the DMA address; this naming was taken over from the C API.

Given that the base DMA address serving as a handle from the perspective of the
C API is just an implementation detail, we should probably just rename this
method to dma_address().

  reply	other threads:[~2026-07-25  0:27 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-24 11:10 [PATCH 0/2] gpu: nova-core: falcon: use I/O projections for DMA transfers Alexandre Courbot
2026-07-24 11:10 ` [PATCH 1/2] gpu: nova-core: falcon: remove unnecessary check Alexandre Courbot
2026-07-24 11:10 ` [PATCH 2/2] gpu: nova-core: falcon: use I/O projection to check transfer bounds Alexandre Courbot
2026-07-24 18:10   ` John Hubbard
2026-07-24 22:27     ` Danilo Krummrich [this message]
2026-07-25  4:42       ` Alexandre Courbot

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