Re: Serializing memory with respect to IN/OUT

[David Young <dyoung%pobox.com@localhost>]

On Thu, Nov 10, 2016 at 10:10:05AM -0600, David Young wrote:
> On Thu, Nov 10, 2016 at 10:52:54AM -0500, Mouse wrote:
> > But the code appears to work in practice.  So I'm clearly missing
> > something.  Have I just not found enough documentation to understand
> > all the effects of LOCK or the xFENCE instructions, or are IN and OUT
> > serialized as if they were memory accesses, or do things just delay
> > long enough that everything happens to get pushed in practice, or what?
> 
> As I recall, there is an interplay of PCI bus ordering rules and x86
> memory-ordering rules such that IN and OUT flush DMA buffers to the
> device.

I should have written, flush DMA buffers to device visibility.

Dave

-- 
David Young
dyoung%pobox.com@localhost    Urbana, IL    (217) 721-9981