[SLOF] [PATCH] Correctly set ibm,my-drc-index

[Alexey Kardashevskiy]

On 09/14/2015 01:57 PM, David Gibson wrote:
> On Sun, 13 Sep 2015 21:25:17 -0500
> Michael Roth <mdroth at linux.vnet.ibm.com> wrote:
>
>> Quoting David Gibson (2015-09-13 18:45:00)
>>> On Fri, 11 Sep 2015 18:48:19 +0200
>>> Laurent Vivier <lvivier at redhat.com> wrote:
>>>
>>>> The current calculation of DRC index for PCI card doesn't take
>>>> into account the PHB bridge index, so with several bridges we
>>>> can have several devices with the same DRC index.
>>>>
>>>> This is a problem when we want to unplug a PCI card with
>>>> drmgr which is based on the DRC index.
>>>>
>>>> Signed-off-by: Laurent Vivier <lvivier at redhat.com>
>>>
>>> Actually, I think the safer fix is just for SLOF not to touch the
>>> ibm,my-drc-index property if it's already present.  QEMU is already
>>> setting it correctly, and SLOF is overwriting it  :(.
>>
>> This patch makes sense and fixes a real bug, but my understanding is that
>> SLOF only fills in properties missing from device node rather than
>> overwriting ones provided by QEMU. On my end, on the second PHB, I see
>> this for a hotplugged device in slot 1 (where prop comes from QEMU via
>> RTAS):
>>
>> mdroth at ubuntu:/proc/device-tree/pci at 800000020000001/pci at 2$ od -x
>> ibm,my-drc-index
>> 0000000 0140 1000
>> 0000004
>>
>> And after reboot (where prop comes from QEMU via SLOF):
>>
>> mdroth at ubuntu:/proc/device-tree/pci at 800000020000001/ethernet at 2$ od -x
>> ibm,my-drc-index
>> 0000000 0140 1000
>> 0000004
>>
>> If you're getting the buggy values (0040 1000, i.e. 40000010 be32 value)
>> it makes me think you're not using the QEMU-generated DTs for device
>> nodes. Older SLOF that doesn't have Nikunj's updates possibly? I think
>> in that case values might get overwritten/thrown out.
>
>
> Ah.  Good point, yes, the downstream qemu doesn't have the code to set
> my-drc-index.
>
> So the question is, do we fix this in SLOF, or do we pull down the qemu
> changes to move more device node creation into qemu, making it moot.


I vote for the latter and do not touch DRC index in SLOF.


>
>
>>
>>>
>>> Adding Mike Roth to CC, since git blame says he wrote this bit of SLOF
>>> code.
>>>
>>>>   slof/fs/pci-properties.fs | 3 ++-
>>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/slof/fs/pci-properties.fs b/slof/fs/pci-properties.fs
>>>> index 4f13402..d132426 100644
>>>> --- a/slof/fs/pci-properties.fs
>>>> +++ b/slof/fs/pci-properties.fs
>>>> @@ -599,9 +599,10 @@
>>>>           pci-reg-props
>>>>           pci-hotplug-enabled IF
>>>>               \ QEMU uses static assignments for my-drc-index:
>>>> -            \ 40000000h + $bus << 8 + $slot << 3
>>>> +            \ 40000000h + $phbindex << 16 + $bus << 8 + $slot << 3
>>>>               dup dup pci-addr2bus 8 lshift
>>>>               swap pci-addr2dev 3 lshift or
>>>> +            puid ff and 10 lshift or
>>>>               40000000 + encode-int s" ibm,my-drc-index" property
>>>>               \ QEMU uses "Slot $bus*32$slotno" for loc-code
>>
>> I think loc-code may need to be updated to match QEMU as well.
>>
>>>>               dup dup pci-addr2bus 20 *
>>>> --
>>>> 2.1.0
>>>>
>>>
>>>
>>> --
>>> David Gibson <dgibson at redhat.com>
>>> Senior Software Engineer, Virtualization, Red Hat
>>
>
>
>
>
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-- 
Alexey