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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.442, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2/25/25 10:14, Zhao Liu wrote: >> impl MemoryRegion { >> // inline to ensure that it is not included in tests, which only >> @@ -174,13 +174,15 @@ pub fn init_io>( >> size: u64, >> ) { >> unsafe { >> - Self::do_init_io(&mut self.inner, owner.cast::(), &ops.0, name, size); >> + Self::do_init_io( >> + self.0.as_mut_ptr(), > > I'm not sure why the wrapper doesn't work here. > > If I change this to `self.as_mut_ptr()`, then compiler tries to apply > `ObjectDeref::as_mut_ptr` and complains: > > the trait `qom::ObjectType` is not implemented for `bindings::MemoryRegion` It's because the implementation of ObjectDeref for "&mut MemoryRegion" wins over coercing "&mut MemoryRegion" to "&MemoryRegion" and then calling MemoryRegion::as_mut_ptr(). I added a comment // self.0.as_mut_ptr() needed because Rust tries to call // ObjectDeref::as_mut_ptr() on "&mut Self", instead of coercing // to "&Self" and then calling MemoryRegion::as_mut_ptr(). // Revisit if/when ObjectCastMut is not needed anymore; it is // only used in a couple places for initialization. Paolo > > But when I modify the function signature to &self like: > > diff --git a/rust/qemu-api/src/memory.rs b/rust/qemu-api/src/memory.rs > index fdb1ea11fcf9..a82348c4a564 100644 > --- a/rust/qemu-api/src/memory.rs > +++ b/rust/qemu-api/src/memory.rs > @@ -167,7 +167,7 @@ unsafe fn do_init_io( > } > > pub fn init_io>( > - &mut self, > + &self, > owner: *mut T, > ops: &'static MemoryRegionOps, > name: &'static str, > > Then the Wrapper's as_mut_ptr() can work. > >> + owner.cast::(), >> + &ops.0, >> + name, >> + size, >> + ); >> } >> } >> - >> - pub(crate) const fn as_mut_ptr(&self) -> *mut bindings::MemoryRegion { >> - addr_of!(self.inner) as *mut _ >> - } >> } >> >> unsafe impl ObjectType for MemoryRegion { >> -- >> 2.48.1 >> >> > >