Re: [Qemu-devel] [PATCH RFC] docs: add PCIe devices placement guidelines

[Marcel Apfelbaum]

On 09/01/2016 04:27 PM, Peter Maydell wrote:
> On 1 September 2016 at 14:22, Marcel Apfelbaum <address@hidden> wrote:
> > Proposes best practices on how to use PCIe/PCI device
> > in PCIe based machines and explain the reasoning behind them.
> >
> > Signed-off-by: Marcel Apfelbaum <address@hidden>
> > ---
> >
> > Hi,
> >
> > Please add your comments on what to add/remove/edit to make this doc usable.

Hi Peter,

> As somebody who doesn't really understand the problem space, my
> thoughts:
>
> (1) is this intended as advice for developers writing machine
> models and adding pci controllers to them, or is it intended as
> advice for users (and libvirt-style management layers) about
> how to configure QEMU?

Is it intended for management layers as they have no way to
understand how to "consume" the Q35 machine,
but also for firmware developers (OVMF/SeaBIOS) to help them
understand the usage model so they can optimize IO/MEM
resources allocation for both boot time and hot-plug.

QEMU users/developers can also benefit from it as the PCIe arch
is more complex supporting both PCI/PCIe devices and
several PCI/PCIe controllers with no clear rules on what goes where.

> (2) it seems to be a bit short on concrete advice (either
> "you should do this" instructions to machine model developers,
> or "use command lines like this" instructions to end-users.

Thanks for the point. I'll be sure to add detailed command line examples
to the next version.

Thanks,
Marcel

> thanks
> -- PMM