Patch "x86/pat: Document the PAT initialization sequence" has been added to the 4.6-stable tree
Subsystems (2)
This is a note to let you know that I've just added the patch titled
x86/pat: Document the PAT initialization sequence
to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-pat-document-the-pat-initialization-sequence.patch
and it can be found in the queue-4.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
b6350c21cfe8aa9d65e189509a23c0ea4b8362c2Mon Sep 17 00:00:00 2001
From: Toshi Kani <[email protected]>
Date: Wed, 23 Mar 2016 15:42:03 -0600
Subject: x86/pat: Document the PAT initialization sequence
From: Toshi Kani <[email protected]>
commit b6350c21cfe8aa9d65e189509a23c0ea4b8362c2 upstream.
Update PAT documentation to describe how PAT is initialized under various configurations.
--- Documentation/x86/pat.txt | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)
Documentation/x86/pat.txt +32 -0
@@ -196,3 +196,35 @@ Another, more verbose way of getting PAT "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. The PAT MSR must be updated by Linux in order to support WC +and WT attributes. Otherwise, the PAT MSR has the value programmed in it +by the firmware. Note, Xen enables WC attribute in the PAT MSR for guests. + + MTRR PAT Call Sequence PAT State PAT MSR + ========================================================= + E E MTRR -> PAT init Enabled OS + E D MTRR -> PAT init Disabled - + D E MTRR -> PAT disable Disabled BIOS + D D MTRR -> PAT disable Disabled - + - np/E PAT -> PAT disable Disabled BIOS + - np/D PAT -> PAT disable Disabled - + E !P/E MTRR -> PAT init Disabled BIOS + D !P/E MTRR -> PAT disable Disabled BIOS + !M !P/E MTRR stub -> PAT disable Disabled 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 + Enabled PAT state set to enabled + Disabled PAT state set to disabled + OS PAT initializes PAT MSR with OS setting + BIOS PAT keeps PAT MSR with BIOS setting +
Patches currently in stable-queue which might be from [email protected] are
queue-4.6/x86-mm-pat-replace-cpu_has_pat-with-boot_cpu_has.patch queue-4.6/x86-mtrr-fix-xorg-crashes-in-qemu-sessions.patch queue-4.6/libnvdimm-pfn-dax-fix-initialization-vs-autodetect-for-mode-alignment.patch queue-4.6/x86-mm-pat-add-support-of-non-default-pat-msr-setting.patch queue-4.6/x86-xen-pat-remove-pat-table-init-code-from-xen.patch queue-4.6/x86-mtrr-fix-pat-init-handling-when-mtrr-is-disabled.patch queue-4.6/x86-mm-pat-add-pat_disable-interface.patch queue-4.6/x86-mm-pat-fix-bug_on-in-mmap_mem-on-qemu-i386.patch queue-4.6/x86-pat-document-the-pat-initialization-sequence.patch