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Subject: Re: [PATCH v3 15/34] parisc: mm: Add p?d_large() definitions
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
Cc:     Steven Price <steven.price@arm.com>, linux-mm@kvack.org,
        Andy Lutomirski <luto@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        James Morse <james.morse@arm.com>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Mark Rutland <Mark.Rutland@arm.com>,
        "Liang, Kan" <kan.liang@linux.intel.com>,
        "James E.J. Bottomley" <jejb@parisc-linux.org>,
        linux-parisc@vger.kernel.org
References: <20190227170608.27963-1-steven.price@arm.com>
 <20190227170608.27963-16-steven.price@arm.com>
 <fa3072ba-f02b-fee5-dc16-d575a5308d4b@gmx.de>
 <20190301221213.snm7cwowr67pdifs@kshutemo-mobl1>
From:   Helge Deller <deller@gmx.de>
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Date:   Tue, 5 Mar 2019 22:45:55 +0100
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On 01.03.19 23:12, Kirill A. Shutemov wrote:
> On Wed, Feb 27, 2019 at 07:54:22PM +0100, Helge Deller wrote:
>> On 27.02.19 18:05, Steven Price wrote:
>>> walk_page_range() is going to be allowed to walk page tables other than
>>> those of user space. For this it needs to know when it has reached a
>>> 'leaf' entry in the page tables. This information is provided by the
>>> p?d_large() functions/macros.
>>>
>>> For parisc, we don't support large pages, so add stubs returning 0.
>>
>> We do support huge pages on parisc, but not yet on those levels.
> 
> Just curious, what level do parisc supports huge pages on?
> AFAICS, it can have 2- or 3- level paging and the patch defines helpers
> for two level: pgd and pmd. Hm?

You are correct.
My comment was misleading and meant to say that we do support generic
huge pages for applications.

Helge