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

From: Logan Gunthorpe
Date: Thu Jun 22 2017 - 16:25:13 EST


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


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