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From: Wedson Almeida Filho <wedsonaf@gmail.com>
Date: Tue, 21 May 2024 00:01:45 -0300
Message-ID: <CANeycqpNeHFUu-RwSc6Ewa3r5TMhYYFDC6bO+sj3OZ398JfJ1A@mail.gmail.com>
Subject: Re: [RFC PATCH 10/11] rust: add basic abstractions for iomem operations
To: Dave Airlie <airlied@gmail.com>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>, Danilo Krummrich <dakr@redhat.com>, 
	gregkh@linuxfoundation.org, rafael@kernel.org, bhelgaas@google.com, 
	ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, 
	gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, 
	a.hindborg@samsung.com, aliceryhl@google.com, fujita.tomonori@gmail.com, 
	lina@asahilina.net, pstanner@redhat.com, ajanulgu@redhat.com, 
	lyude@redhat.com, rust-for-linux@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
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On Mon, 20 May 2024 at 23:07, Dave Airlie <airlied@gmail.com> wrote:
>
> >
> > Wedson wrote a similar abstraction in the past
> > (`rust/kernel/io_mem.rs` in the old `rust` branch), with a
> > compile-time `SIZE` -- it is probably worth taking a look.
> >
>
> Just on this point, we can't know in advance what size the IO BARs are
> at compile time.
>
> The old method just isn't useful for real devices with runtime IO BAR sizes.

The compile-time `SIZE` in my implementation is a minimum size.

Attempts to read/write with constants within that size (offset + size)
were checked at compile time, that is, they would have zero additional
runtime cost when compared to C. Reads/writes beyond the minimum would
have to be checked at runtime.