On Tue, 11 Nov 2008 15:11:40 +0900

Paul Mundt  wrote:
> On Sun, Nov 09, 2008 at 11:26:46AM -0800, Andrew Morton wrote:

quoted text
> > (cc linux-arch)

> >

> > > It seems that architectures that provide readq/writeq are

> > > mips, parisc and x86 (and x86_64).

> > >

> There are more than that, grep arch/*/include also.

>

> In addition to mips, parisc, and x86, there is ia64, alpha, sh, and

> sparc.

I didn't noticed these functions, thanks.
>

quoted text
> > #ifdef readq

> >

> > Is a suitable way of determining whether the architecture implements

> > readq and writeq.  It isn't pretty, but it will suffice.

> >

> > A problem with it is that drivers will then do

> >

> > #ifndef readq

> >

> > #endif

> >

> > which rather sucks - we don't want lots of little private readq/writeq

> > implementations all over the tree.

> >

> > Perhaps it would be better to have a CONFIG_ARCH_HAS_READQ and to then

> > disable these drivers on the architectures which don't provide

> > readq/writeq support.

> >

> However this is handled, we don't want a rehash of the read/writes{b,w,l} fiasco.

>

> Allowing drivers to do their own local implementations of these things

> has always been a complete disaster. A Kconfig option will at least take

> care of having these craptastic ifdef lists for architectures in every

> driver that rolls its own implementation.

>

> Even a sub-optimal asm-generic version would be preferable, if the

> semantics are well enough defined and consistently adhered to.

I found nice source file, lib/iomap.c.

There are architecture independent read/write{b,w,l} (named like ioread8).
I want to implement architecture independent readq/writeq in lib/iomap.c .

Andrew told,
> Perhaps it would be better to have a CONFIG_ARCH_HAS_READQ and to then

quoted text
> disable these drivers on the architectures which don't provide

> readq/writeq support.

But I want to use x38_edac.c on x86_32 environment,

and I think similar desire may occur in the future.
Is this way good enough? Request for comment.

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