Hey Jan,
>> >> Note that Linux's arm32 atomics helpers use the READ_ONCE() and >> WRITE_ONCE() macros defined in <asm-generic/rwonce.h>, while Linux's >> arm64 atomics helpers use __READ_ONCE() and __WRITE_ONCE(). > > And our ACCESS_ONCE() can't be used, or be made usable? I don't think > we want a 3rd variant when we're already in the process of discussing > how to fold the two ones we have right now. Many thanks for the pointer, I'm still familiarising myself with Xen's codebase and wasn't aware of ACCESS_ONCE(); yes, that's exactly what we need which means we can drop Linux's <asm-generic/rwonce.h> completely. That also means: > > I don't think weakening the checking is a good idea when the macros > are being made available for general use. If they'd be renamed to be > private flavors for use just in Arm's atomics, this would be a > different thing. This problem goes away, as does the need/desire to bump the minimum GCC version up to 4.9 for xen/arm just to support the usage of C11 _Generic in Linux's <linux/compiler_types.h>. That said, agreed, I did think the way I'd done it was a tad suspect hence the "possibly contentious" disclaimer :-) I'll keep this in mind for similar porting work in future. >> >> \ No newline at end of file > > This wants taking care of in any event - there are multiple instances > in this patch (in fact it looks as if all of the new files had this > issue), and I didn't check others. Ack, will fix. Thanks for taking the time to provide feedback! Cheers, Ash.
