linux-kernel - Re: [PATCH 0/7] Pre-requisite patches for mm and irq in nova-core

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Message-Id: <DDONM9Z1XF2T.32OBDFX7FONJY@nvidia.com>
Date: Wed, 22 Oct 2025 15:57:59 +0900
From: "Alexandre Courbot" <acourbot@...dia.com>
To: "Joel Fernandes" <joelagnelf@...dia.com>,
 <linux-kernel@...r.kernel.org>, <rust-for-linux@...r.kernel.org>,
 <dri-devel@...ts.freedesktop.org>, <dakr@...nel.org>, <acourbot@...dia.com>
Cc: "Alistair Popple" <apopple@...dia.com>, "Miguel Ojeda"
 <ojeda@...nel.org>, "Alex Gaynor" <alex.gaynor@...il.com>, "Boqun Feng"
 <boqun.feng@...il.com>, "Gary Guo" <gary@...yguo.net>,
 <bjorn3_gh@...tonmail.com>, "Benno Lossin" <lossin@...nel.org>, "Andreas
 Hindborg" <a.hindborg@...nel.org>, "Alice Ryhl" <aliceryhl@...gle.com>,
 "Trevor Gross" <tmgross@...ch.edu>, "David Airlie" <airlied@...il.com>,
 "Simona Vetter" <simona@...ll.ch>, "Maarten Lankhorst"
 <maarten.lankhorst@...ux.intel.com>, "Maxime Ripard" <mripard@...nel.org>,
 "Thomas Zimmermann" <tzimmermann@...e.de>, "John Hubbard"
 <jhubbard@...dia.com>, "Timur Tabi" <ttabi@...dia.com>,
 <joel@...lfernandes.org>, "Elle Rhumsaa" <elle@...thered-steel.dev>,
 "Daniel Almeida" <daniel.almeida@...labora.com>,
 <nouveau@...ts.freedesktop.org>
Subject: Re: [PATCH 0/7] Pre-requisite patches for mm and irq in nova-core

On Tue Oct 21, 2025 at 3:55 AM JST, Joel Fernandes wrote:
> These patches have some prerequistes needed for nova-core as support is added
> for memory management and interrupt handling. I rebased them on drm-rust-next
> and would like them to be considered for the next merge window. I also included
> a simple rust documentation patch fixing some issues I noticed while reading it :).
>
> The series adds support for the PRAMIN aperture mechanism, which is a
> prerequisite for virtual memory as it is required to boot strap virtual memory
> (we cannot write to VRAM using virtual memory because we need to write page
> tables to VRAM in the first place).
>
> I also add page table related structures (mm/types.rs) using the bitfield
> macro, which will be used for page table walking, memory mapping, etc. This is
> currently unused code, because without physical memory allocation (using the
> buddy allocator), we cannot use this code as page table pages need to be
> allocated in the first place. However, I have included several examples in the
> file about how these structures will be used. I have also simplified the code
> keeping future additions to it for later.
>
> For interrupts, I only have added additional support for GSP's message queue
> interrupt. I am working on adding support to the interrupt controller module
> (VFN) which is the next thing for me to post after this series. I have it
> prototyped and working, however I am currently making several changes to it
> related to virtual functions. For now in this series, I just want to get the
> GSP-specific patch out of the way, hence I am including it here.
>
> I also have added a patch for bitfield macro which constructs a bitfield struct
> given its storage type. This is used in a later GSP interrupt patch in the
> series to read from one register and write to another.

So IIUC, this series contains the following:

1. Add PRAMIN support,
2. Add Page mapping support, albeit this is unexercised until we have a
   user (e.g. buddy allocator),
3. Add Falcon interrupt support,
4. Add missing bitfield functionality, albeit not used yet,
5. Various documentation patches.

This is a bit confusing, as there is close to no logical relationship or
dependency between these patches. I see potential for several different
submissions here:

- The core documentation fix, as Miguel pointed out, since it should be
  merged into the rust tree and not nova-core.
- The bitfield patch is a useful addition and should be sent separately.
- PRAMIN/Page mapping should come with code that exercices them, so
  think they belong as the first patches of a series that ends with
  basic memory allocation capabilities. But feel free to send a RFC if
  you want early feedback.
- The falcon interrupts patch does not seem to be used by the last two
  patches? I guess it belongs to the series that will add support for
  the interrupt controller.
- Other documentation patches belong to the series that introduces the
  feature they document.