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Re: [Qemu-ppc] [PATCH] spapr/pci: populate PCI DT in reverse order
From: |
Thomas Huth |
Subject: |
Re: [Qemu-ppc] [PATCH] spapr/pci: populate PCI DT in reverse order |
Date: |
Tue, 1 Dec 2015 22:48:38 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 30/11/15 11:45, Greg Kurz wrote:
> Since commit 1d2d974244c6 "spapr_pci: enumerate and add PCI device tree", QEMU
> populates the PCI device tree in the opposite order compared to SLOF.
>
> Before 1d2d974244c6:
>
> Populating /address@hidden
> 00 0000 (D) : 1af4 1000 virtio [ net ]
> 00 0800 (D) : 1af4 1001 virtio [ block ]
> 00 1000 (D) : 1af4 1009 virtio [ network ]
> Populating /address@hidden/address@hidden
>
>
> 7e5294b8 : /address@hidden
> 7e52b998 : |-- address@hidden
> 7e52c0c8 : |-- address@hidden
> 7e52c7e8 : +-- address@hidden ok
>
> Since 1d2d974244c6:
>
> Populating /address@hidden
> 00 1000 (D) : 1af4 1009 virtio [ network ]
> Populating /address@hidden/address@hidden
> 00 0800 (D) : 1af4 1001 virtio [ block ]
> 00 0000 (D) : 1af4 1000 virtio [ net ]
>
>
> 7e5e8118 : /address@hidden
> 7e5ea6a0 : |-- address@hidden
> 7e5eadb8 : |-- address@hidden
> 7e5eb4d8 : +-- address@hidden ok
>
> This behaviour change is not actually a bug since no assumptions should be
> made on DT ordering. But it has no real justification either, other than
> being the consequence of the way fdt_add_subnode() inserts new elements
> to the front of the FDT rather than adding them to the tail.
>
> This patch reverts to the historical SLOF ordering by walking PCI devices in
> reverse order.
I've applied your patch here locally, and indeed, the device tree looks
nicer to me, too, when the nodes are listed in ascending order.
Tested-by: Thomas Huth <address@hidden>
- Re: [Qemu-ppc] [PATCH] spapr/pci: populate PCI DT in reverse order,
Thomas Huth <=