Re: [Qemu-devel] Re: [PATCH 00/10] pci: pci_register_bar_simple

[Michael S. Tsirkin]

On Tue, Apr 05, 2011 at 12:05:08AM +0300, Blue Swirl wrote:
> On Mon, Apr 4, 2011 at 10:44 PM, Michael S. Tsirkin <address@hidden> wrote:
> > On Mon, Apr 04, 2011 at 08:02:23PM +0300, Blue Swirl wrote:
> >> On Mon, Apr 4, 2011 at 7:35 PM, Avi Kivity <address@hidden> wrote:
> >> > On 04/04/2011 07:22 PM, Anthony Liguori wrote:
> >> >>
> >> >> On 04/04/2011 10:59 AM, Michael S. Tsirkin wrote:
> >> >>>
> >> >>> On Mon, Apr 04, 2011 at 06:27:57PM +0300, Avi Kivity wrote:
> >> >>>>
> >> >>>> Many PCI BARs that use the memory address space map a single MMIO 
> >> >>>> region
> >> >>>> into
> >> >>>> the entire BAR range.  Introduce an API pci_register_bar_simple() for
> >> >>>> that use
> >> >>>> case, and convert all users where this can be done trivially.
> >> >>>>
> >> >>>> This will reduce the work required to introduce a PCI memory API; it's
> >> >>>> also
> >> >>>> a nice code reduction in its own right.
> >> >>>
> >> >>> This will save some code, so
> >> >>> Acked-by: Michael S. Tsirkin<address@hidden>
> >> >>>
> >> >>> I really hope the rest of devices will follow.
> >> >>
> >> >> How complete is this?
> >> >
> >> > I converted all devices which were easy to convert.  There may be one or 
> >> > two
> >> > more that can be converted with additional work (and perhaps with an
> >> > additional pic_bar_get_current_address() API, and a 
> >> > pci_bar_set_coalescing()
> >> > API).  The rest likely need to stick with the callback-based API.
> >>
> >> In my version which I sent earlier but didn't commit, also other BARs
> >> besides the first one and also tricky devices like VGA were handled.
> >
> > Yes, I liked that patchset too. What happened to it?
> 
> Nothing, but I thought that there could be a "perfect" solution.
> 
> I like in Avi's version that unnecessary API changes are avoided.

Yes, it's nice that it's incremental.

> >> But I didn't commit it because I felt it was not going to right
> >> direction. I think the BARs should be specified in PCIDeviceInfo
> >> instead of adding more function calls. The same applies to this patch
> >> set.
> >
> > Is that really that fundamental? What I do care about is
> > making pci.c track and register all device memory
> > so that we can finally implement pci bridge features
> > such as master abort handling and unmapped memory.
> 
> The structure version can be done later. Right, pci.c should manage
> the device mappings.

OK, so applying Avi's patchset and building on that is
your preferred approach too?

-- 
MST