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

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

There are plenty of “always 1” bits in the kernel VAs... we steal some of those to represent flags and just OR them back in when the bus space accesses are done.

-- thorpej
Sent from my iPhone.

> On Dec 2, 2019, at 11:30 AM, Andrew Doran <ad%netbsd.org@localhost> wrote:
> 
> On Mon, Dec 02, 2019 at 07:03:50PM +0000, Andrew Doran wrote:
> 
>> I think the way to avoid both of those would be key off the bus_space_tag_t. 
> 
> Ah it can't be in the tag.  If we do it, it has to be via the handle.  Since
> the same tag can be used with different options.
> 
> Andrew