From: Bjorn Helgaas <helgaas@kernel.org>
To: Zhi Wang <zhiw@nvidia.com>
Cc: rust-for-linux@vger.kernel.org, dakr@kernel.org,
bhelgaas@google.com, kwilczynski@kernel.org, ojeda@kernel.org,
alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net,
bjorn3_gh@protonmail.com, lossin@kernel.org,
a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
cjia@nvidia.com, smitra@nvidia.com, ankita@nvidia.com,
aniketa@nvidia.com, kwankhede@nvidia.com, targupta@nvidia.com,
zhiwang@kernel.org, acourbot@nvidia.com, joelagnelf@nvidia.com,
jhubbard@nvidia.com, markus.probst@posteo.de
Subject: Re: [PATCH v3 3/5] rust: pci: add a helper to query configuration space size
Date: Thu, 30 Oct 2025 11:51:15 -0500 [thread overview]
Message-ID: <20251030165115.GA1636169@bhelgaas> (raw)
In-Reply-To: <20251030154842.450518-4-zhiw@nvidia.com>
On Thu, Oct 30, 2025 at 03:48:40PM +0000, Zhi Wang wrote:
> Expose a safe Rust wrapper for the `cfg_size` field of `struct pci_dev`,
> allowing drivers to query the size of a device's configuration space.
>
> This is useful for code that needs to know whether the device supports
> extended configuration space (e.g. 256 vs 4096 bytes) when accessing PCI
> configuration registers and apply runtime checks.
What is the value of knowing the config space size, as opposed to just
having config space accessors return PCIBIOS_BAD_REGISTER_NUMBER or
similar when trying to read past the implemented size?
Apart from pci-sysfs and vfio, I don't really see any drivers that use
pdev->cfg_size today.
next prev parent reply other threads:[~2025-10-30 16:51 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-30 15:48 [PATCH v3 0/5] rust: pci: add config space read/write support Zhi Wang
2025-10-30 15:48 ` [PATCH v3 1/5] rust: io: factor common I/O helpers into Io trait Zhi Wang
2025-10-31 9:07 ` Alice Ryhl
2025-10-31 12:48 ` Zhi Wang
2025-10-31 12:55 ` Danilo Krummrich
2025-10-30 15:48 ` [PATCH v3 2/5] rust: io: factor out MMIO read/write macros Zhi Wang
2025-10-30 15:48 ` [PATCH v3 3/5] rust: pci: add a helper to query configuration space size Zhi Wang
2025-10-30 16:51 ` Bjorn Helgaas [this message]
2025-10-31 12:16 ` Zhi Wang
2025-10-31 12:46 ` Danilo Krummrich
2025-10-30 15:48 ` [PATCH v3 4/5] rust: pci: add config space read/write support Zhi Wang
2025-10-31 12:48 ` Danilo Krummrich
2025-10-31 12:50 ` Zhi Wang
2025-10-30 15:48 ` [PATCH v3 5/5] sample: rust: pci: add tests for config space routines Zhi Wang
2025-10-31 12:50 ` Danilo Krummrich
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