Re: Why NetBSD x86's bus_space_barrier does not use [sml]fence?

[Jason Thorpe <thorpej%me.com@localhost>]

> On Dec 2, 2019, at 11:03 AM, Andrew Doran <ad%netbsd.org@localhost> wrote:
> 
> I think the way to avoid both of those would be key off the bus_space_tag_t. 
> There are already two, one for I/O and one for memory.  We could do multiple
> memory tags.  That's probably very easy, I think the harder bit would likely
> be passing those down to PCI and having it choose.  I don't know that code.

The problem is that the bus_space API doesn't have a way to give you a new tag if you have specified PREFETCHABLE in the bus_space_map() call.

-- thorpej