Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86: (613 commits)
  x86: standalone trampoline code
  x86: move suspend wakeup code to C
  x86: coding style fixes to arch/x86/kernel/acpi/sleep.c
  x86: setup_trampoline() - fix section mismatch warning
  x86: section mismatch fixes, #1
  x86: fix paranoia about using BIOS quickboot mechanism.
  x86: print out buggy mptable
  x86: use cpu_online()
  x86: use cpumask_of_cpu()
  x86: remove unnecessary tmp local variable
  x86: remove unnecessary memset()
  x86: use ioapic_read_entry() and ioapic_write_entry()
  x86: avoid redundant loop in io_apic_level_ack_pending()
  x86: remove superfluous initialisation in boot code.
  x86: merge mpparse_{32,64}.c
  x86: unify mp_register_gsi
  x86: unify mp_config_acpi_legacy_irqs
  x86: unify mp_register_ioapic
  x86: unify uniq_io_apic_id
  x86: unify smp_scan_config
  ...

1 files changed, 100 insertions, 0 deletions

diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt
new file mode 100644
index 0000000..17965f9
--- /dev/null
+++ b/Documentation/x86/pat.txt
@@ -0,0 +1,100 @@
+
+PAT (Page Attribute Table)
+
+x86 Page Attribute Table (PAT) allows for setting the memory attribute at the
+page level granularity. PAT is complementary to the MTRR settings which allows
+for setting of memory types over physical address ranges. However, PAT is
+more flexible than MTRR due to its capability to set attributes at page level
+and also due to the fact that there are no hardware limitations on number of
+such attribute settings allowed. Added flexibility comes with guidelines for
+not having memory type aliasing for the same physical memory with multiple
+virtual addresses.
+
+PAT allows for different types of memory attributes. The most commonly used
+ones that will be supported at this time are Write-back, Uncached,
+Write-combined and Uncached Minus.
+
+There are many different APIs in the kernel that allows setting of memory
+attributes at the page level. In order to avoid aliasing, these interfaces
+should be used thoughtfully. Below is a table of interfaces available,
+their intended usage and their memory attribute relationships. Internally,
+these APIs use a reserve_memtype()/free_memtype() interface on the physical
+address range to avoid any aliasing.
+
+
+-------------------------------------------------------------------
+API                    |    RAM   |  ACPI,...  |  Reserved/Holes  |
+-----------------------|----------|------------|------------------|
+                       |          |            |                  |
+ioremap                |    --    |    UC      |       UC         |
+                       |          |            |                  |
+ioremap_cache          |    --    |    WB      |       WB         |
+                       |          |            |                  |
+ioremap_nocache        |    --    |    UC      |       UC         |
+                       |          |            |                  |
+ioremap_wc             |    --    |    --      |       WC         |
+                       |          |            |                  |
+set_memory_uc          |    UC    |    --      |       --         |
+ set_memory_wb         |          |            |                  |
+                       |          |            |                  |
+set_memory_wc          |    WC    |    --      |       --         |
+ set_memory_wb         |          |            |                  |
+                       |          |            |                  |
+pci sysfs resource     |    --    |    --      |       UC         |
+                       |          |            |                  |
+pci sysfs resource_wc  |    --    |    --      |       WC         |
+ is IORESOURCE_PREFETCH|          |            |                  |
+                       |          |            |                  |
+pci proc               |    --    |    --      |       UC         |
+ !PCIIOC_WRITE_COMBINE |          |            |                  |
+                       |          |            |                  |
+pci proc               |    --    |    --      |       WC         |
+ PCIIOC_WRITE_COMBINE  |          |            |                  |
+                       |          |            |                  |
+/dev/mem               |    --    |    UC      |       UC         |
+ read-write            |          |            |                  |
+                       |          |            |                  |
+/dev/mem               |    --    |    UC      |       UC         |
+ mmap SYNC flag        |          |            |                  |
+                       |          |            |                  |
+/dev/mem               |    --    |  WB/WC/UC  |    WB/WC/UC      |
+ mmap !SYNC flag       |          |(from exist-|  (from exist-    |
+ and                   |          |  ing alias)|    ing alias)    |
+ any alias to this area|          |            |                  |
+                       |          |            |                  |
+/dev/mem               |    --    |    WB      |       WB         |
+ mmap !SYNC flag       |          |            |                  |
+ no alias to this area |          |            |                  |
+ and                   |          |            |                  |
+ MTRR says WB          |          |            |                  |
+                       |          |            |                  |
+/dev/mem               |    --    |    --      |    UC_MINUS      |
+ mmap !SYNC flag       |          |            |                  |
+ no alias to this area |          |            |                  |
+ and                   |          |            |                  |
+ MTRR says !WB         |          |            |                  |
+                       |          |            |                  |
+-------------------------------------------------------------------
+
+Notes:
+
+-- in the above table mean "Not suggested usage for the API". Some of the --'s
+are strictly enforced by the kernel. Some others are not really enforced
+today, but may be enforced in future.
+
+For ioremap and pci access through /sys or /proc - The actual type returned
+can be more restrictive, in case of any existing aliasing for that address.
+For example: If there is an existing uncached mapping, a new ioremap_wc can
+return uncached mapping in place of write-combine requested.
+
+set_memory_[uc|wc] and set_memory_wb should be used in pairs, where driver will
+first make a region uc or wc and switch it back to wb after use.
+
+Over time writes to /proc/mtrr will be deprecated in favor of using PAT based
+interfaces. Users writing to /proc/mtrr are suggested to use above interfaces.
+
+Drivers should use ioremap_[uc|wc] to access PCI BARs with [uc|wc] access
+types.
+
+Drivers should use set_memory_[uc|wc] to set access type for RAM ranges.
+