Am 07.08.19 um 12:41 schrieb Christoph Hellwig: > On Wed, Aug 07, 2019 at 08:53:25AM +0000, Koenig, Christian wrote: >> Am 07.08.19 um 09:08 schrieb Christoph Hellwig: >>> On Wed, Aug 07, 2019 at 10:56:40AM +0800, Tao Zhou wrote: >>>> readq/writeq are not supported on all architectures >>> NAK. You must not use atomic_* on __iomem (MMIO) memory. >> Well then what's the right thing to do here? >> >> Essentially writeq/readq doesn't seems to be available on all >> architectures either. > writeq/readq are provided whenever the CPU actually supports 64-bit > atomic loads and stores. Is there a config option which we can make the driver depend on? I mean that ARM doesn't support 64bit atomic loads and stores on MMIO is quite a boomer for us. Toa do you of hand know what we actually need the 64bit atomic stores for? E.g. what is the hardware background? Regards, Christian. > If it doesn't provide them atomic64* is > not going to be atomic vs the I/O device either. And that is on top > of the fact that for various architectures you can't simply use > plain loads and stores on MMIO memory to start with, which is why > we have the special accessors and the __iomem annotation.
