Hi, The background is that I'm reviewing Wedson's PR on IoMem for Rust-for-Linux project: https://github.com/Rust-for-Linux/linux/pull/462 readX() and writeX() are used to provide Rust code to read/write IO memory. And I want to find whether we need to check the alignment of the pointer. I wonder whether the addresses passed to readX() and writeX() need to be aligned to the size of the accesses (e.g. the parameter of readl() has to be a 4-byte aligned pointer). The only related information I get so far is the following quote in Documentation/driver-io/device-io.rst: On many platforms, I/O accesses must be aligned with respect to the access size; failure to do so will result in an exception or unpredictable results. Does it mean all readX() and writeX() need to use aligned addresses? Or the alignment requirement is arch-dependent, i.e. if the architecture supports and has enabled misalignment load and store, no alignment requirement on readX() and writeX(), otherwise still need to use aligned addresses. I know different archs have their own alignment requirement on memory accesses, just want to make sure the requirement of the readX() and writeX() APIs. Thanks a lot! Regards, Boqun
