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Subject: Re: [PATCH 06/13] mm: pagewalk: Add 'depth' parameter to pte_hole
To:     William Kucharski <william.kucharski@oracle.com>
Cc:     "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
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References: <20190215170235.23360-1-steven.price@arm.com>
 <20190215170235.23360-7-steven.price@arm.com>
 <52690905-1755-46BD-940B-1EE4CEA5F795@oracle.com>
From:   Steven Price <steven.price@arm.com>
Message-ID: <76ce9f9b-eb0d-6ad5-9f57-ff3a8fa6b074@arm.com>
Date:   Wed, 20 Feb 2019 14:10:45 +0000
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On 20/02/2019 11:35, William Kucharski wrote:
> 
> 
>> On Feb 15, 2019, at 10:02 AM, Steven Price <Steven.Price@arm.com> wrote:
>>
>> The pte_hole() callback is called at multiple levels of the page tables.
>> Code dumping the kernel page tables needs to know what at what depth
>> the missing entry is. Add this is an extra parameter to pte_hole().
>> When the depth isn't know (e.g. processing a vma) then -1 is passed.
>>
>> Note that depth starts at 0 for a PGD so that PUD/PMD/PTE retain their
>> natural numbers as levels 2/3/4.
> 
> Nit: Could you add a comment noting this for anyone wondering how to
> calculate the level numbers in the future?

Good point! I'll expand the comment in the header file.

Thanks,

Steve