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Message-ID: <563AF8B3.8030907@linux.intel.com>
Date: Thu, 5 Nov 2015 14:35:31 +0800
From: Jiang Liu <jiang.liu@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Keith Busch <keith.busch@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
linux-pci@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Bryan Veal <bryan.e.veal@...el.com>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Martin Mares <mj@....cz>,
Jon Derrick <jonathan.derrick@...el.com>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC PATCHv3 3/4] x86/pci: Initial commit for new VMD device
driver
On 2015/11/4 23:14, Thomas Gleixner wrote:
> On Wed, 4 Nov 2015, Keith Busch wrote:
>
>> On Tue, Nov 03, 2015 at 12:42:02PM +0100, Thomas Gleixner wrote:
>>> On Tue, 3 Nov 2015, Keith Busch wrote:
>>>>>> + msi_irqdomain = pci_msi_create_irq_domain(NULL, &pci_chained_msi_domain_info,
>>>>>> + vmd_irqdomain);
>>>
>>> But that parent limitation does not matter simply because your
>>> msi_irqdomain does not follow down the hierarchy in the allocation
>>> path.
>>>
>>> So we can avoid the vmd_irqdomain creation completely. It's just
>>> wasting memory and has no value at all. Creating the msi domain with a
>>> NULL parent is possible.
>>
>> I'm having trouble following the hierarchy and didn't understand the
>> connection between the parent and msi comain. It's still new to me,
>> but I don't think a NULL parent is allowable with msi domains:
>>
>> pci_msi_setup_msi_irqs()
>> pci_msi_domain_alloc_irqs()
>> msi_domain_alloc_irqs()
>> __irq_domain_alloc_irqs()
>> irq_domain_alloc_irqs_recursive()
>> msi_domain_alloc()
>> irq_domain_alloc_irqs_parent()
>>
>> The last call returns -ENOSYS since there parent is NULL. Was the
>> intension to allow no parent, or do I still need to allocate one to
>> achieve the desired chaining?
>
> Hmm, seems I missed that part. But that's a fixable problem. Jiang?
Hi Keith,
Could you please try the attached patch?
Thanks!
Gerry
>
> Thanks,
>
> tglx
>
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View attachment "0001-msi-Relax-msi_domain_alloc-to-support-parentless-MSI.patch" of type "text/x-patch" (1267 bytes)
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