Re: [PATCH 04/12] rust: qdev: add clock creation

[Zhao Liu <zhao1.liu@intel.com>]

On Fri, Feb 07, 2025 at 11:16:15AM +0100, Paolo Bonzini wrote:
> Date: Fri,  7 Feb 2025 11:16:15 +0100
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: [PATCH 04/12] rust: qdev: add clock creation
> X-Mailer: git-send-email 2.48.1
> 
> Add a Rust version of qdev_init_clock_in, which can be used in
> instance_init.  There are a couple differences with the C
> version:
> 
> - in Rust the object keeps its own reference to the clock (in addition to
>   the one embedded in the NamedClockList), and the reference is dropped
>   automatically by instance_finalize(); this is encoded in the signature
>   of DeviceClassMethods::init_clock_in, which makes the lifetime of the
>   clock independent of that of the object it holds.  This goes unnoticed
>   in the C version and is due to the existence of aliases.
> 
> - also, anything that happens during instance_init uses the pinned_init
>   framework to operate on a partially initialized object, and is done
>   through class methods (i.e. through DeviceClassMethods rather than
>   DeviceMethods) because the device does not exist yet.  Therefore, Rust
>   code *must* create clocks from instance_init, which is stricter than C.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  rust/hw/char/pl011/src/device.rs |  43 +++++-------
>  rust/qemu-api/src/prelude.rs     |   2 +
>  rust/qemu-api/src/qdev.rs        | 109 ++++++++++++++++++++++++++++++-
>  rust/qemu-api/src/vmstate.rs     |   4 +-
>  4 files changed, 127 insertions(+), 31 deletions(-)
>

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>