From: Andrew Donnellan > Sent: 27 January 2023 03:21 > > On Thu, 2023-01-26 at 17:31 +0000, David Laight wrote: > > Changing the size to kzalloc() doesn't help. > > The alignment depends on the allocator and is only required to have > > a relatively small alignment (ARCH_MINALIGN?) regardless of the size. > > > > IIRC one of the allocators adds a small header to every item. > > It won't return 16 byte aligned items at all. > > I'm relying on the behaviour described in Documentation/core- > api/memory-allocation.rst: > > The address of a chunk allocated with kmalloc is aligned to at > least ARCH_KMALLOC_MINALIGN bytes. For sizes which are a power of > two, the alignment is also guaranteed to be at least the respective > size. > > Is this wrong? The alignment for power of two doesn't match what I've inferred from reading comments on other patches. It is true for dma_malloc_coherent() - that does guarantee that a 16k allocate will be aligned on a 16k physical address boundary. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
