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From: Toshi Kani <toshi.kani@hp.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: akpm@linux-foundation.org, hpa@zytor.com, tglx@linutronix.de,
	mingo@redhat.com, arnd@arndb.de, linux-mm@kvack.org,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	dave.hansen@intel.com, Elliott@hp.com
Subject: Re: [PATCH v3 3/6] mm: Change ioremap to set up huge I/O mappings
Date: Wed, 04 Mar 2015 16:15:39 -0700	[thread overview]
Message-ID: <1425510939.17007.271.camel@misato.fc.hp.com> (raw)
In-Reply-To: <20150304220912.GA22518@gmail.com>

On Wed, 2015-03-04 at 23:09 +0100, Ingo Molnar wrote:
> * Toshi Kani <toshi.kani@hp.com> wrote:
 :
> Hm, so I don't see where you set the proper x86 PAT table attributes 
> for the pmds.
> 
> MTRR's are basically a legacy mechanism, the proper way to set cache 
> attribute is PAT and I don't see where this generic code does that, 
> but I might be missing something?

It's done by x86 code, not by this generic code.  __ioremap_caller()
takes page_cache_mode and converts it to pgprot_t using the PAT table
attribute.  It then calls this generic func, ioremap_page_range().  When
creating a huge page mapping, pud_set_huge() and pmd_set_huge() handle
the relocation of the PAT bit.

Thanks,
-Toshi    


  reply	other threads:[~2015-03-04 23:16 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-03 17:44 [PATCH v3 0/6] Kernel huge I/O mapping support Toshi Kani
2015-03-03 17:44 ` [PATCH v3 1/6] mm: Change __get_vm_area_node() to use fls_long() Toshi Kani
2015-03-03 17:44 ` [PATCH v3 2/6] lib: Add huge I/O map capability interfaces Toshi Kani
2015-03-03 17:44 ` [PATCH v3 3/6] mm: Change ioremap to set up huge I/O mappings Toshi Kani
2015-03-04 22:09   ` Ingo Molnar
2015-03-04 23:15     ` Toshi Kani [this message]
2015-03-03 17:44 ` [PATCH v3 4/6] mm: Change vunmap to tear down huge KVA mappings Toshi Kani
2015-03-03 17:44 ` [PATCH v3 5/6] x86, mm: Support huge I/O mapping capability I/F Toshi Kani
2015-03-03 17:44 ` [PATCH v3 6/6] x86, mm: Support huge KVA mappings on x86 Toshi Kani
2015-03-03 22:44   ` Andrew Morton
2015-03-03 23:14     ` Toshi Kani
2015-03-04  1:00       ` Andrew Morton
2015-03-04 16:23         ` Toshi Kani
2015-03-04 20:17           ` Ingo Molnar
2015-03-04 21:16             ` Toshi Kani

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