From: "H. Peter Anvin" <hpa@zytor.com>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "mingo@elte.hu" <mingo@elte.hu>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"tvignaud@mandriva.com" <tvignaud@mandriva.com>
Subject: Re: [patch] x86, pat: fix reserve_memtype() for legacy 1MB range
Date: Fri, 09 Jan 2009 14:55:55 -0800 [thread overview]
Message-ID: <4967D5FB.5020302@zytor.com> (raw)
In-Reply-To: <20090109224804.GD6472@linux-os.sc.intel.com>
Suresh Siddha wrote:
> On Fri, Jan 09, 2009 at 02:39:31PM -0800, H. Peter Anvin wrote:
>> Suresh Siddha wrote:
>>> Here X is trying to map first 8KB of memory using /dev/mem. Existing
>>> code treats first 0-4KB of memory as non-RAM and 4KB-8KB as RAM. Recent
>>> code changes don't allow to map memory with different attributes
>>> at the same time.
>>>
>> Why was 0-4 KB marked as non-RAM? It is most definitely RAM, and should
>> be WB.
>
> While in reality it is RAM, we have CONFIG_STRICT_DEVMEM which doesn't allow
> apps to map RAM pages using /dev/mem. And to allow app's to map the
> legacy 0-4KB bios data page, we consider it as non-RAM.
Permission to map and memory type should not be connected. Just to
clarify, when mapped, was it still WB?
-hpa
next prev parent reply other threads:[~2009-01-09 22:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-09 22:35 [patch] x86, pat: fix reserve_memtype() for legacy 1MB range Suresh Siddha
2009-01-09 22:39 ` H. Peter Anvin
2009-01-09 22:48 ` Suresh Siddha
2009-01-09 22:55 ` H. Peter Anvin [this message]
2009-01-09 23:13 ` Suresh Siddha
2009-01-09 23:26 ` H. Peter Anvin
2009-01-11 2:07 ` Ingo Molnar
2009-01-17 17:42 ` Pavel Machek
2009-01-17 23:24 ` H. Peter Anvin
2009-01-18 8:08 ` Pavel Machek
2009-01-19 18:45 ` Suresh Siddha
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