From: Borislav Petkov <bp@suse.de>
To: Toshi Kani <toshi.kani@hpe.com>
Cc: jgross@suse.com, mcgrof@suse.com, x86@kernel.org,
linux-kernel@vger.kernel.org, paul.gortmaker@windriver.com,
hpa@zytor.com, xen-devel@lists.xenproject.org,
tglx@linutronix.de, mingo@kernel.org, elliott@hpe.com
Subject: Re: [PATCH v2 6/6] x86/pat: Document PAT initializations
Date: Tue, 22 Mar 2016 18:02:22 +0100 [thread overview]
Message-ID: <20160322170222.GG5656__28808.4323205569$1458666214$gmane$org@pd.tnic> (raw)
In-Reply-To: <1458175619-32206-5-git-send-email-toshi.kani@hpe.com>
On Wed, Mar 16, 2016 at 06:46:59PM -0600, Toshi Kani wrote:
> 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
Err "PAT MSR must be updated by Linux in order to support WC and WT" ... or so?
> +to support WC and WT attributes. Otherwise, PAT keeps PAT MSR value set
> +by BIOS.
"Otherwise, the PAT MSR has the value programmed in it by the firmware."
> 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
s/Enable/Enabled/
MTRR->pat_init() - either use function names for both or do pseudo like
so:
MTRR init -> PAT init
> + E D MTRR -> pat_init() Disable -
s/Disable/Disabled/. Ditto for the rest.
> + 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
> +
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
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next prev parent reply other threads:[~2016-03-22 17:02 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 ` [PATCH v2 6/6] x86/pat: Document PAT initializations Toshi Kani
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 ` Borislav Petkov [this message]
[not found] ` <20160322170222.GG5656@pd.tnic>
2016-03-22 22:15 ` [PATCH v2 6/6] x86/pat: Document PAT initializations 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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