Messages in this thread | | | From | Jesse Barnes <> | Subject | Re: [PATCH] I/O space write barrier | Date | Mon, 4 Oct 2004 14:20:01 -0700 |
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On Monday, October 4, 2004 1:39 pm, Albert Cahalan wrote: > > diff -Nru a/include/asm-ppc/io.h b/include/asm-ppc/io.h > > --- a/include/asm-ppc/io.h 2004-09-27 10:48:41 -07:00 > > +++ b/include/asm-ppc/io.h 2004-09-27 10:48:41 -07:00 > > @@ -197,6 +197,8 @@ > > #define memcpy_fromio(a,b,c) memcpy((a),(void *)(b),(c)) > > #define memcpy_toio(a,b,c) memcpy((void *)(a),(b),(c)) > > > > +#define mmiowb() asm volatile ("eieio" ::: "memory") > > + > > /* > > * Map in an area of physical address space, for accessing > > * I/O devices etc. > > I don't think this is right. For ppc, eieio is > already included as part of the assembly for the > IO operations. If you could delete that, great, > but I suspect that nearly all drivers would break.
Ok, if it's covered than mmiowb() can just be empty for ppc.
> BTW, the "eieio" name is better. The "wb" part > of "mmiowb" looks like "write back" to me, as if > it were some sort of cache push operation. It is > also lacking an appropriate song. :-)
It's supposed to be 'write barrier' just like wmb is a write memory barrier, so is mmiowb a memory-mapped I/O write barrier. Make sense?
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