MMIO and gcc re-ordering issue
torvalds at linux-foundation.org
Wed May 28 08:02:15 EST 2008
On Tue, 27 May 2008, Matthew Wilcox wrote:
> On Tue, May 27, 2008 at 10:38:22PM +0100, Alan Cox wrote:
> > > re-ordering, even though I doubt it will be visible in practice. So if you
> > > use the "__" versions, you'd better have barriers even on x86!
> > Are we also going to have __ioread*/__iowrite* ?
> Didn't we already define ioread*() to have loose semantics?
They are supposed to have the same semantics as readl/writel.
And yes, it's "loose", but only when compared to inb/outb (which are
really very strict, if you want to emulate x86 - an "outb" basically is
not only ordered, it doesn't even post the write, and waits until it has
hit the bus!)
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