On 2011-05-19 15:35, Anthony Liguori wrote: > On 05/19/2011 08:26 AM, Avi Kivity wrote: >> On 05/19/2011 04:23 PM, Anthony Liguori wrote: >>>> Actually, things are a bit more complicated: This layer has to properly >>>> adopt the coalescing properties of underlying regions or we cause >>>> performance regressions to VGA emulation. That means it has to register >>>> dispatching slots of the corresponding size and set the coalescing flag >>>> accordingly. And it likely need to adjust them as the regions below >>>> change. >>> >>> >>> As I mentioned in another thread, I don't think we want to "design" >>> coalescing into the API. Coalescing is something that breaks through >>> abstractions layers and is really just a hack. >> >> It's impossible not to design it into the API. The layer which wants to >> do coalescing (the device) has no idea if and where its memory is mapped. > > There's two places coalescing currently matters: VGA and PCI devices. > Since VGA is just a special PCI device, let's just focus on PCI devices.
Every frame buffer device, PCI or not, benefits from it. Don't focus on PCI or x86. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux
