linux-kernel - Re: [PATCH v6 13/14] arm64, acpi, numa: NUMA support based on SRAT and SLIT

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Date:	Thu, 12 May 2016 08:27:08 -0700
From:	David Daney <ddaney@...iumnetworks.com>
To:	Catalin Marinas <catalin.marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Will Deacon <will.deacon@....com>
CC:	David Daney <ddaney@...iumnetworks.com>,
	Mark Rutland <mark.rutland@....com>,
	<linux-ia64@...r.kernel.org>, David Daney <david.daney@...ium.com>,
	Lv Zheng <lv.zheng@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Frank Rowand <frowand.list@...il.com>, <x86@...nel.org>,
	Robert Moore <robert.moore@...el.com>,
	<linux-acpi@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>,
	Grant Likely <grant.likely@...aro.org>,
	Len Brown <lenb@...nel.org>, Fenghua Yu <fenghua.yu@...el.com>,
	Marc Zyngier <Marc.Zyngier@....com>,
	Jon Masters <jcm@...hat.com>,
	Robert Richter <rrichter@...ium.com>,
	Rob Herring <robh+dt@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	<linux-arm-kernel@...ts.infradead.org>, <devel@...ica.org>,
	Tony Luck <tony.luck@...el.com>,
	<linux-kernel@...r.kernel.org>, Hanjun Guo <hanjun.guo@...aro.org>,
	Ganapatrao Kulkarni <gkulkarni@...iumnetworks.com>
Subject: Re: [PATCH v6 13/14] arm64, acpi, numa: NUMA support based on SRAT
 and SLIT

On 05/12/2016 02:49 AM, Catalin Marinas wrote:
> On Wed, May 11, 2016 at 05:06:13PM -0700, David Daney wrote:
>> On 05/11/2016 03:39 AM, Catalin Marinas wrote:
[...]
>>>
>>> I wonder whether you could replace the get_mpidr_in_madt() function with
>>> something like acpi_get_phys_id(). It looks like get_mpidr_in_madt()
>>> duplicates functionality already available elsewhere.
>>
>> I just tried that, and it doesn't work.
>>
>> The problem is that this code is being run very early in the boot, and
>> kmalloc cannot be used.  acpi_get_phys_id() and its ilk can only be used
>> once we have working kmalloc.  We need to extract the NUMA information early
>> like this precisely because it is needed to initializing the slab system
>>
>> Notice that we are using early_acpi_os_unmap_memory() et al. in
>> get_mpidr_in_madt() explicitly for this reason.
>>
>> In summary: I don't think we need another revision of this patch, it is like
>> this for a good reason.
>
> Slightly confusing, in another reply you said you are going to address
> my comment. So, is it doable?

I don't think so.

My previous reply, to the thread in 0/14, was prematurely made with the 
incorrect assumption that it was a simple change.  Now, after really 
digging in to the code, and attempting to do as you suggested, I have 
changed my mind.

As I indicated above, there are no remaining suggestions or requests for 
changes to this patch set pending action.  Unless people find additional 
problems, I think it is ready for merging.

I know that Will and Rafael were discussing the proper timing for 
merging this in the other thread, so I leave it in their hands at this 
point.

Thanks,
David Daney


>