diff options
| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-07-01 15:23:10 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-07-03 17:06:57 +0100 |
| commit | 9ab79bb22cc77adcca5ebbadea6caec6a478f283 (patch) | |
| tree | 24332575bd5376a261ce621297903c8623f7ccd4 | |
| parent | 20a1080dff2f1be8933baa0d910c41882c7279ee (diff) | |
ARM: pgtable: document mapping types
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | arch/arm/include/asm/pgtable-2level.h | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h index bfd662e49a25..aeddd28b3595 100644 --- a/arch/arm/include/asm/pgtable-2level.h +++ b/arch/arm/include/asm/pgtable-2level.h @@ -129,7 +129,36 @@ /* * These are the memory types, defined to be compatible with - * pre-ARMv6 CPUs cacheable and bufferable bits: XXCB + * pre-ARMv6 CPUs cacheable and bufferable bits: n/a,n/a,C,B + * ARMv6+ without TEX remapping, they are a table index. + * ARMv6+ with TEX remapping, they correspond to n/a,TEX(0),C,B + * + * MT type Pre-ARMv6 ARMv6+ type / cacheable status + * UNCACHED Uncached Strongly ordered + * BUFFERABLE Bufferable Normal memory / non-cacheable + * WRITETHROUGH Writethrough Normal memory / write through + * WRITEBACK Writeback Normal memory / write back, read alloc + * MINICACHE Minicache N/A + * WRITEALLOC Writeback Normal memory / write back, write alloc + * DEV_SHARED Uncached Device memory (shared) + * DEV_NONSHARED Uncached Device memory (non-shared) + * DEV_WC Bufferable Normal memory / non-cacheable + * DEV_CACHED Writeback Normal memory / write back, read alloc + * VECTORS Variable Normal memory / variable + * + * All normal memory mappings have the following properties: + * - reads can be repeated with no side effects + * - repeated reads return the last value written + * - reads can fetch additional locations without side effects + * - writes can be repeated (in certain cases) with no side effects + * - writes can be merged before accessing the target + * - unaligned accesses can be supported + * + * All device mappings have the following properties: + * - no access speculation + * - no repetition (eg, on return from an exception) + * - number, order and size of accesses are maintained + * - unaligned accesses are "unpredictable" */ #define L_PTE_MT_UNCACHED (_AT(pteval_t, 0x00) << 2) /* 0000 */ #define L_PTE_MT_BUFFERABLE (_AT(pteval_t, 0x01) << 2) /* 0001 */ |