Re: [PATCH 2/2] pci: Use Qemu created PCI device nodes

From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: Thomas Huth <thuth@redhat.com>,
	Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Cc: linuxppc-dev@ozlabs.org, david@gibson.dropbear.id.au
Subject: Re: [PATCH 2/2] pci: Use Qemu created PCI device nodes
Date: Sat, 25 Apr 2015 17:31:55 +1000	[thread overview]
Message-ID: <553B42EB.6080803@ozlabs.ru> (raw)
In-Reply-To: <20150424213058.2889af29@thh440s>

On 04/25/2015 05:30 AM, Thomas Huth wrote:
>
>   Hi Nikunj,
>
> On Wed, 22 Apr 2015 16:27:20 +0530
> Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
>
>> PCI Enumeration has been part of SLOF. Now with hotplug code addition
>> in Qemu, it makes more sense to have this code a one place, i.e. Qemu.
>
> s/Qemu/QEMU/ and s/code a one place/code in one place/ ?
>
>> Adding routines to walk through the device nodes created by Qemu. SLOF
>> will configure the device/bridges and program the BARs for
>> communicating with the devices.
>
> I wonder whether it would make more sense to also set up the BARs etc.
> in QEMU instead of SLOF?

We need BAR setup in 2 cases: when SLOF needs to boot from a PCI device 
(and SLOF can do BAR setup) and when we do PCI hotplug - and BARs are set 
by the guest, otherwise we hit races here (Michael Roth can tell more). So 
as for today there is no reason for doing this in QEMU.

-- 
Alexey