diff options
Diffstat (limited to 'Documentation/x86')
| -rw-r--r-- | Documentation/x86/kernel-stacks | 2 | ||||
| -rw-r--r-- | Documentation/x86/mtrr.txt | 20 | ||||
| -rw-r--r-- | Documentation/x86/zero-page.txt | 3 |
3 files changed, 19 insertions, 6 deletions
diff --git a/Documentation/x86/kernel-stacks b/Documentation/x86/kernel-stacks index 0f3a6c201943..9a0aa4d3a866 100644 --- a/Documentation/x86/kernel-stacks +++ b/Documentation/x86/kernel-stacks @@ -16,7 +16,7 @@ associated with each CPU. These stacks are only used while the kernel is in control on that CPU; when a CPU returns to user space the specialized stacks contain no useful data. The main CPU stacks are: -* Interrupt stack. IRQSTACKSIZE +* Interrupt stack. IRQ_STACK_SIZE Used for external hardware interrupts. If this is the first external hardware interrupt (i.e. not a nested hardware interrupt) then the diff --git a/Documentation/x86/mtrr.txt b/Documentation/x86/mtrr.txt index 860bc3adc223..dc3e703913ac 100644 --- a/Documentation/x86/mtrr.txt +++ b/Documentation/x86/mtrr.txt @@ -6,10 +6,22 @@ Luis R. Rodriguez <mcgrof@do-not-panic.com> - April 9, 2015 =============================================================================== Phasing out MTRR use -MTRR use is replaced on modern x86 hardware with PAT. Over time the only type -of effective MTRR that is expected to be supported will be for write-combining. -As MTRR use is phased out device drivers should use arch_phys_wc_add() to make -MTRR effective on non-PAT systems while a no-op on PAT enabled systems. +MTRR use is replaced on modern x86 hardware with PAT. Direct MTRR use by +drivers on Linux is now completely phased out, device drivers should use +arch_phys_wc_add() in combination with ioremap_wc() to make MTRR effective on +non-PAT systems while a no-op but equally effective on PAT enabled systems. + +Even if Linux does not use MTRRs directly, some x86 platform firmware may still +set up MTRRs early before booting the OS. They do this as some platform +firmware may still have implemented access to MTRRs which would be controlled +and handled by the platform firmware directly. An example of platform use of +MTRRs is through the use of SMI handlers, one case could be for fan control, +the platform code would need uncachable access to some of its fan control +registers. Such platform access does not need any Operating System MTRR code in +place other than mtrr_type_lookup() to ensure any OS specific mapping requests +are aligned with platform MTRR setup. If MTRRs are only set up by the platform +firmware code though and the OS does not make any specific MTRR mapping +requests mtrr_type_lookup() should always return MTRR_TYPE_INVALID. For details refer to Documentation/x86/pat.txt. diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt index 82fbdbc1e0b0..95a4d34af3fd 100644 --- a/Documentation/x86/zero-page.txt +++ b/Documentation/x86/zero-page.txt @@ -17,7 +17,8 @@ Offset Proto Name Meaning (struct ist_info) 080/010 ALL hd0_info hd0 disk parameter, OBSOLETE!! 090/010 ALL hd1_info hd1 disk parameter, OBSOLETE!! -0A0/010 ALL sys_desc_table System description table (struct sys_desc_table) +0A0/010 ALL sys_desc_table System description table (struct sys_desc_table), + OBSOLETE!! 0B0/010 ALL olpc_ofw_header OLPC's OpenFirmware CIF and friends 0C0/004 ALL ext_ramdisk_image ramdisk_image high 32bits 0C4/004 ALL ext_ramdisk_size ramdisk_size high 32bits |