From: Toshi Kani <toshi.kani@hpe.com>
To: mingo@kernel.org, bp@suse.de, hpa@zytor.com, tglx@linutronix.de
Cc: jgross@suse.com, Toshi Kani <toshi.kani@hpe.com>,
mcgrof@suse.com, x86@kernel.org, linux-kernel@vger.kernel.org,
paul.gortmaker@windriver.com, xen-devel@lists.xenproject.org,
elliott@hpe.com
Subject: [PATCH v2 6/6] x86/pat: Document PAT initializations
Date: Wed, 16 Mar 2016 18:46:59 -0600 [thread overview]
Message-ID: <1458175619-32206-5-git-send-email-toshi.kani__42590.0695882321$1458172563$gmane$org@hpe.com> (raw)
In-Reply-To: <1458175619-32206-1-git-send-email-toshi.kani@hpe.com>
Update PAT documentation to describe how PAT is initialized under
various configurations.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
Documentation/x86/pat.txt | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt
index 54944c7..f619e1d 100644
--- a/Documentation/x86/pat.txt
+++ b/Documentation/x86/pat.txt
@@ -196,3 +196,35 @@ Another, more verbose way of getting PAT related debug messages is with
"debugpat" boot parameter. With this parameter, various debug messages are
printed to dmesg log.
+PAT Initialization
+------------------
+
+The following table describes how PAT is initialized under various
+configurations. PAT must be set to enable to initialize PAT MSR in order
+to support WC and WT attributes. Otherwise, PAT keeps PAT MSR value set
+by BIOS. Note, Xen enables WC attribute in BIOS setup for guests.
+
+ MTRR PAT Call Sequence PAT State PAT MSR
+ =========================================================
+ E E MTRR -> pat_init() Enable OS
+ E D MTRR -> pat_init() Disable -
+ D E MTRR -> pat_disable() Disable BIOS
+ D D MTRR -> pat_disable() Disable -
+ - np/E nopat() -> pat_disable() Disable BIOS
+ - np/D nopat() -> pat_disable() Disable -
+ E !P/E MTRR -> pat_init() Disable BIOS
+ D !P/E MTRR -> pat_disable() Disable BIOS
+ !M !P/E MTRR stub -> pat_disable() Disable BIOS
+
+ Legend
+ ------------------------------------------------
+ E Feature enabled in CPU
+ D Feature disabled/unsupported in CPU
+ np "nopat" boot option specified
+ !P CONFIG_X86_PAT option unset
+ !M CONFIG_MTRR option unset
+ Enable PAT state set to enable
+ Disable PAT state set to disable
+ OS PAT initializes PAT MSR with OS setup
+ BIOS PAT keeps PAT MSR with BIOS setup
+
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next prev parent reply other threads:[~2016-03-16 23:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-17 0:46 [PATCH v2 2/6] x86/mm/pat: Add pat_disable() interface Toshi Kani
2016-03-17 0:46 ` [PATCH v2 3/6] x86/mtrr: Fix Xorg crashes in Qemu sessions Toshi Kani
2016-03-17 0:46 ` [PATCH v2 4/6] x86/mtrr: Fix PAT init handling when MTRR MSR is disabled Toshi Kani
2016-03-17 0:46 ` [PATCH v2 5/6] x86/xen, pat: Remove PAT table init code from Xen Toshi Kani
2016-03-17 0:46 ` Toshi Kani [this message]
2016-03-22 16:59 ` [PATCH v2 2/6] x86/mm/pat: Add pat_disable() interface Borislav Petkov
[not found] ` <1458175619-32206-2-git-send-email-toshi.kani@hpe.com>
2016-03-22 17:00 ` [PATCH v2 3/6] x86/mtrr: Fix Xorg crashes in Qemu sessions Borislav Petkov
[not found] ` <20160322170047.GD5656@pd.tnic>
2016-03-22 21:53 ` Toshi Kani
[not found] ` <1458683610.6393.624.camel@hpe.com>
2016-03-23 8:44 ` Borislav Petkov
[not found] ` <20160323084437.GB8031@pd.tnic>
2016-03-23 15:53 ` Toshi Kani
[not found] ` <1458748393.6393.653.camel@hpe.com>
2016-03-23 21:47 ` Toshi Kani
[not found] ` <1458175619-32206-3-git-send-email-toshi.kani@hpe.com>
2016-03-22 17:01 ` [PATCH v2 4/6] x86/mtrr: Fix PAT init handling when MTRR MSR is disabled Borislav Petkov
[not found] ` <20160322170135.GE5656@pd.tnic>
2016-03-22 22:02 ` Toshi Kani
[not found] ` <1458175619-32206-4-git-send-email-toshi.kani@hpe.com>
2016-03-22 17:02 ` [PATCH v2 5/6] x86/xen, pat: Remove PAT table init code from Xen Borislav Petkov
[not found] ` <20160322170206.GF5656@pd.tnic>
2016-03-23 6:08 ` Juergen Gross
[not found] ` <1458175619-32206-5-git-send-email-toshi.kani@hpe.com>
2016-03-22 17:02 ` [PATCH v2 6/6] x86/pat: Document PAT initializations Borislav Petkov
[not found] ` <20160322170222.GG5656@pd.tnic>
2016-03-22 22:15 ` Toshi Kani
[not found] ` <20160322165944.GC5656@pd.tnic>
2016-03-22 21:40 ` [PATCH v2 2/6] x86/mm/pat: Add pat_disable() interface Toshi Kani
[not found] ` <1458682845.6393.614.camel@hpe.com>
2016-03-23 8:51 ` Borislav Petkov
[not found] ` <20160323085141.GC8031@pd.tnic>
2016-03-23 15:49 ` Toshi Kani
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