Re: [PATCH 08/12] drm/tyr: add MMU module

[Deborah Brouwer <deborah.brouwer@collabora.com>]

On Sat, Feb 21, 2026 at 11:20:17AM +0000, Alice Ryhl wrote:
> On Wed, Feb 11, 2026 at 05:37:09PM -0800, Deborah Brouwer wrote:
> > From: Boris Brezillon <boris.brezillon@collabora.com>
> > 
> > Add a Memory Management Unit (MMU) driver for Tyr. The MMU wraps a
> > SlotManager for allocating hardware address space slots. The underlying
> > AddressSpaceManager performs MMU operations including enabling/disabling
> > address spaces, flushing page tables, and locking regions for page table
> > updates.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > Co-developed-by: Deborah Brouwer <deborah.brouwer@collabora.com>
> > Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
> 
> > +/// Any resource/information that will be used by the AddressSpaceManager
> > +/// to make a VM active is present in VmAsData.
> > +///
> > +/// On activation, we will pass an Arc<VmAsData> that will be stored in
> > +/// the slot to make sure the page table and the underlying resources
> > +/// (pages) used by the AS slot won't go away while the MMU points to
> > +/// those.
> > +pub(crate) struct VmAsData {
> > +    /// Tracks this VM's binding to a hardware address space slot.
> > +    as_seat: LockedBy<Seat, AsSlotManager>,
> > +    /// Hardware configuration for this address space.
> > +    as_config: AddressSpaceConfig,
> > +    /// Page table (managed by devres).
> > +    pub(crate) page_table: Pin<KBox<Devres<IoPageTable<ARM64LPAES1>>>>,
> 
> I don't think the Box is needed if you #[pin] this field.

Ok, for v2, I moved the page table initialization from struct Vm to struct VmAsData
in the address_space.rs which allows us to construct it in place and #[pin] it.

> 
> Alice