Re: [PATCH 03/17] pnv_phb3.h: change TYPE_PNV_PHB3_ROOT_BUS name

From: Daniel Henrique Barboza <danielhb413@gmail.com>
To: "Cédric Le Goater" <clg@kaod.org>, qemu-devel@nongnu.org
Cc: qemu-ppc@nongnu.org, david@gibson.dropbear.id.au
Subject: Re: [PATCH 03/17] pnv_phb3.h: change TYPE_PNV_PHB3_ROOT_BUS name
Date: Mon, 3 Jan 2022 16:01:41 -0300	[thread overview]
Message-ID: <e947fdf3-1aec-4257-d5dc-9765ad8e34e8@gmail.com> (raw)
In-Reply-To: <49139a66-ea8b-b599-d7c4-e40597e558f3@kaod.org>

On 1/3/22 05:28, Cédric Le Goater wrote:
> On 12/28/21 20:37, Daniel Henrique Barboza wrote:
>> The TYPE_PNV_PHB3_ROOT_BUS name is used as the default bus name when
>> the dev has no 'id'. However, pnv-phb3-root-bus is a bit too long to be
>> used as a bus name.
>>
>> Most common QEMU buses and PCI controllers are named based on their bus
>> type (e.g. pSeries spapr-pci-host-bridge is called 'pci'). The most
>> common name for a PCIE bus controller in QEMU is 'pcie'. Naming it
>> 'pcie' would break the documented use of the pnv-phb3 device, since
>> 'pcie.0' would now refer to the root bus instead of the first root port.
>>
>> There's nothing particularly wrong with the 'root-bus' name used before,
>> aside from the fact that 'root-bus' is being used for pnv-phb3 and
>> pnv-phb4 created buses, which is not quite correct since these buses
>> aren't implemented the same way in QEMU - you can't plug a
>> pnv-phb4-root-port into a pnv-phb3 root bus, for example.
>>
>> This patch renames it as 'phb3-root', which is a compromise between the
>> existing and the previously used name. Creating 3 phbs without ID will
>> result in an "info qtree" output similar to this:
>>
>> bus: main-system-bus
>>    type System
>>    dev: pnv-phb3, id ""
>>      index = 2 (0x2)
>>      chip-id = 0 (0x0)
>>      x-config-reg-migration-enabled = true
>>      bypass-iommu = false
>>      bus: phb3-root.2
>>        type phb3-root
>>    dev: pnv-phb3, id ""
>>      index = 1 (0x1)
>>      chip-id = 0 (0x0)
>>      x-config-reg-migration-enabled = true
>>      bypass-iommu = false
>>      bus: phb3-root.1
>>        type phb3-root
>>    dev: pnv-phb3, id ""
>>      index = 0 (0x0)
>>      chip-id = 0 (0x0)
>>      x-config-reg-migration-enabled = true
>>      bypass-iommu = false
>>      bus: phb3-root.0
>>        type phb3-root
>>
>> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
>> ---
>>   include/hw/pci-host/pnv_phb3.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/hw/pci-host/pnv_phb3.h b/include/hw/pci-host/pnv_phb3.h
>> index 2e423c3890..658ee40e13 100644
>> --- a/include/hw/pci-host/pnv_phb3.h
>> +++ b/include/hw/pci-host/pnv_phb3.h
>> @@ -105,7 +105,7 @@ struct PnvPBCQState {
>>   /*
>>    * PHB3 PCIe Root port
>>    */
>> -#define TYPE_PNV_PHB3_ROOT_BUS "pnv-phb3-root-bus"
>> +#define TYPE_PNV_PHB3_ROOT_BUS "phb3-root"
> 
> hmm, what about "pnv-phb3-root" ? I like the 'pnv' prefix to identify
> the machine.

Works for me. I'll make the change in v2.

Thanks,

Daniel

> 
> 
> Thanks,
> 
> C.
> 
> 
> 
>>   #define TYPE_PNV_PHB3_ROOT_PORT "pnv-phb3-root-port"
>>
> 