[Qemu-devel] KVM call minutes for 2014-05-13

[Markus Armbruster]

Today's agenda:

- QOMifying both Memory regions and GPIOs and attaching them via QOM
  links (Peter Crosthwaite)

Here are my notes; please correct mistakes.

Peter C: Everything with a connection becomes a QOM object, references
become links
Peter Maydell: Okay

PC: Don't include address spaces in v1, just memory regions and GPIO
PM: Okay

What's the root memory region's canonical path?
PM: There is no root

What about the big memory region in exec.c?
PM: Should go away eventually

Andreas Färber: Converting to types is a no-brainer, but property names
and such are ABI, need to be very careful

What's the connection to Edgar's CPU work?

AF: Not everyone one the call is a memory API expert, please explain
address space and memory regions
PM: Address space is flattended memory regions, needed for actual memory
access
when constructing machines, we deal with memory regions, not address
spaces

AF+PM: Each CPU should have its own address space

Does this duplicate address spaces?
PM: Yes, but it's okay, because
(a) they don't change very often
(b) if performance turns out to suffer, we can cache or share

AF: How much memory do address spaces use?
PM: Don't know, guess not much

Do busmasters get their own address space, too?
PM: Yes

Back to canonical paths
Can we get them right?  [I missed details here]

Where to start?
PC[?] suggests softip [I almost certainly got this name wrong]
has CPUs with private memory, good example for separate address spaces

How do separate address spaces affect gdbstub?
threads can have their own view of memory already, we should be fine

AF: Does per-CPU address space imply per-CPU memory regions?
PM: Not necessarily, depends on board

Back to canonical path of memory region
AF: the memory region object needs to go *somewhere*!
possible solution: if board code doesn't put the global memory region
anywhere, put it in machine/unattached

When does a QOM object need a path?
AF: it should always have a path, but it really needs one when it's
referenced via QMP or by a link

General direction seems uncontroversial

PC intends to post patches soon

How is this work connected to vfio hotplug, and how to move best vfio
hotplug forward?

Alex Graf intends to respin his platform device patches