Re: [PATCH 3/7] asm-generic/io.h: make ioread64 and iowrite64 universally available

Logan Gunthorpe
2017-06-22T20:25:12Z

On 6/22/2017 2:14 PM, Alan Cox wrote:
> If a platform doesn't support 64bit I/O operations from the CPU then you
> either need to use some kind of platform/architecture specific interface
> if present or accept you don't have one.

Yes, I understand that.

The thing is that every user that's currently using it right now is
patching in their own version that splits it on non-64bit systems.

> It's not safe to split it. Possibly for some use cases you could add an
> ioread64_maysplit()

I'm open to doing something like that.

> What btw is the actual ARM compiler warning ? Is the compiler also trying
> to tell you it's a bad idea ?

It's just the compiler noting that you are mixing volatile and
non-volatile pointers. Strangely some io{read|write}XX use volatile but
most do not. But it's nothing crazy.

Logan