diff options
| -rw-r--r-- | Documentation/x86/pat.txt | 54 |
1 files changed, 45 insertions, 9 deletions
diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt index 17965f927c15..c93ff5f4c0dd 100644 --- a/Documentation/x86/pat.txt +++ b/Documentation/x86/pat.txt | |||
| @@ -14,6 +14,10 @@ PAT allows for different types of memory attributes. The most commonly used | |||
| 14 | ones that will be supported at this time are Write-back, Uncached, | 14 | ones that will be supported at this time are Write-back, Uncached, |
| 15 | Write-combined and Uncached Minus. | 15 | Write-combined and Uncached Minus. |
| 16 | 16 | ||
| 17 | |||
| 18 | PAT APIs | ||
| 19 | -------- | ||
| 20 | |||
| 17 | There are many different APIs in the kernel that allows setting of memory | 21 | There are many different APIs in the kernel that allows setting of memory |
| 18 | attributes at the page level. In order to avoid aliasing, these interfaces | 22 | attributes at the page level. In order to avoid aliasing, these interfaces |
| 19 | should be used thoughtfully. Below is a table of interfaces available, | 23 | should be used thoughtfully. Below is a table of interfaces available, |
| @@ -26,38 +30,38 @@ address range to avoid any aliasing. | |||
| 26 | API | RAM | ACPI,... | Reserved/Holes | | 30 | API | RAM | ACPI,... | Reserved/Holes | |
| 27 | -----------------------|----------|------------|------------------| | 31 | -----------------------|----------|------------|------------------| |
| 28 | | | | | | 32 | | | | | |
| 29 | ioremap | -- | UC | UC | | 33 | ioremap | -- | UC- | UC- | |
| 30 | | | | | | 34 | | | | | |
| 31 | ioremap_cache | -- | WB | WB | | 35 | ioremap_cache | -- | WB | WB | |
| 32 | | | | | | 36 | | | | | |
| 33 | ioremap_nocache | -- | UC | UC | | 37 | ioremap_nocache | -- | UC- | UC- | |
| 34 | | | | | | 38 | | | | | |
| 35 | ioremap_wc | -- | -- | WC | | 39 | ioremap_wc | -- | -- | WC | |
| 36 | | | | | | 40 | | | | | |
| 37 | set_memory_uc | UC | -- | -- | | 41 | set_memory_uc | UC- | -- | -- | |
| 38 | set_memory_wb | | | | | 42 | set_memory_wb | | | | |
| 39 | | | | | | 43 | | | | | |
| 40 | set_memory_wc | WC | -- | -- | | 44 | set_memory_wc | WC | -- | -- | |
| 41 | set_memory_wb | | | | | 45 | set_memory_wb | | | | |
| 42 | | | | | | 46 | | | | | |
| 43 | pci sysfs resource | -- | -- | UC | | 47 | pci sysfs resource | -- | -- | UC- | |
| 44 | | | | | | 48 | | | | | |
| 45 | pci sysfs resource_wc | -- | -- | WC | | 49 | pci sysfs resource_wc | -- | -- | WC | |
| 46 | is IORESOURCE_PREFETCH| | | | | 50 | is IORESOURCE_PREFETCH| | | | |
| 47 | | | | | | 51 | | | | | |
| 48 | pci proc | -- | -- | UC | | 52 | pci proc | -- | -- | UC- | |
| 49 | !PCIIOC_WRITE_COMBINE | | | | | 53 | !PCIIOC_WRITE_COMBINE | | | | |
| 50 | | | | | | 54 | | | | | |
| 51 | pci proc | -- | -- | WC | | 55 | pci proc | -- | -- | WC | |
| 52 | PCIIOC_WRITE_COMBINE | | | | | 56 | PCIIOC_WRITE_COMBINE | | | | |
| 53 | | | | | | 57 | | | | | |
| 54 | /dev/mem | -- | UC | UC | | 58 | /dev/mem | -- | WB/WC/UC- | WB/WC/UC- | |
| 55 | read-write | | | | | 59 | read-write | | | | |
| 56 | | | | | | 60 | | | | | |
| 57 | /dev/mem | -- | UC | UC | | 61 | /dev/mem | -- | UC- | UC- | |
| 58 | mmap SYNC flag | | | | | 62 | mmap SYNC flag | | | | |
| 59 | | | | | | 63 | | | | | |
| 60 | /dev/mem | -- | WB/WC/UC | WB/WC/UC | | 64 | /dev/mem | -- | WB/WC/UC- | WB/WC/UC- | |
| 61 | mmap !SYNC flag | |(from exist-| (from exist- | | 65 | mmap !SYNC flag | |(from exist-| (from exist- | |
| 62 | and | | ing alias)| ing alias) | | 66 | and | | ing alias)| ing alias) | |
| 63 | any alias to this area| | | | | 67 | any alias to this area| | | | |
| @@ -68,7 +72,7 @@ pci proc | -- | -- | WC | | |||
| 68 | and | | | | | 72 | and | | | | |
| 69 | MTRR says WB | | | | | 73 | MTRR says WB | | | | |
| 70 | | | | | | 74 | | | | | |
| 71 | /dev/mem | -- | -- | UC_MINUS | | 75 | /dev/mem | -- | -- | UC- | |
| 72 | mmap !SYNC flag | | | | | 76 | mmap !SYNC flag | | | | |
| 73 | no alias to this area | | | | | 77 | no alias to this area | | | | |
| 74 | and | | | | | 78 | and | | | | |
| @@ -98,3 +102,35 @@ types. | |||
| 98 | 102 | ||
| 99 | Drivers should use set_memory_[uc|wc] to set access type for RAM ranges. | 103 | Drivers should use set_memory_[uc|wc] to set access type for RAM ranges. |
| 100 | 104 | ||
| 105 | |||
| 106 | PAT debugging | ||
| 107 | ------------- | ||
| 108 | |||
| 109 | With CONFIG_DEBUG_FS enabled, PAT memtype list can be examined by | ||
| 110 | |||
| 111 | # mount -t debugfs debugfs /sys/kernel/debug | ||
| 112 | # cat /sys/kernel/debug/x86/pat_memtype_list | ||
| 113 | PAT memtype list: | ||
| 114 | uncached-minus @ 0x7fadf000-0x7fae0000 | ||
| 115 | uncached-minus @ 0x7fb19000-0x7fb1a000 | ||
| 116 | uncached-minus @ 0x7fb1a000-0x7fb1b000 | ||
| 117 | uncached-minus @ 0x7fb1b000-0x7fb1c000 | ||
| 118 | uncached-minus @ 0x7fb1c000-0x7fb1d000 | ||
| 119 | uncached-minus @ 0x7fb1d000-0x7fb1e000 | ||
| 120 | uncached-minus @ 0x7fb1e000-0x7fb25000 | ||
| 121 | uncached-minus @ 0x7fb25000-0x7fb26000 | ||
| 122 | uncached-minus @ 0x7fb26000-0x7fb27000 | ||
| 123 | uncached-minus @ 0x7fb27000-0x7fb28000 | ||
| 124 | uncached-minus @ 0x7fb28000-0x7fb2e000 | ||
| 125 | uncached-minus @ 0x7fb2e000-0x7fb2f000 | ||
| 126 | uncached-minus @ 0x7fb2f000-0x7fb30000 | ||
| 127 | uncached-minus @ 0x7fb31000-0x7fb32000 | ||
| 128 | uncached-minus @ 0x80000000-0x90000000 | ||
| 129 | |||
| 130 | This list shows physical address ranges and various PAT settings used to | ||
| 131 | access those physical address ranges. | ||
| 132 | |||
| 133 | Another, more verbose way of getting PAT related debug messages is with | ||
| 134 | "debugpat" boot parameter. With this parameter, various debug messages are | ||
| 135 | printed to dmesg log. | ||
| 136 | |||