Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1359467
| From | Toshi Kani <toshi.kani@hpe.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v2 6/6] x86/pat: Document PAT initializations |
| Date | 2016-03-17 01:00 +0100 |
| Message-ID | <rdtw7-7MK-17@gated-at.bofh.it> (permalink) |
| References | <rdtw6-7MK-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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 +
Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread
[PATCH v2 2/6] x86/mm/pat: Add pat_disable() interface Toshi Kani <toshi.kani@hpe.com> - 2016-03-17 01:00 +0100 [PATCH v2 4/6] x86/mtrr: Fix PAT init handling when MTRR MSR is disabled Toshi Kani <toshi.kani@hpe.com> - 2016-03-17 01:00 +0100 [PATCH v2 3/6] x86/mtrr: Fix Xorg crashes in Qemu sessions Toshi Kani <toshi.kani@hpe.com> - 2016-03-17 01:00 +0100 [PATCH v2 5/6] x86/xen,pat: Remove PAT table init code from Xen Toshi Kani <toshi.kani@hpe.com> - 2016-03-17 01:00 +0100 [PATCH v2 6/6] x86/pat: Document PAT initializations Toshi Kani <toshi.kani@hpe.com> - 2016-03-17 01:00 +0100
csiph-web