On 16.03.16 18:55, Andreas Färber wrote:
Am 15.03.2016 um 18:21 schrieb Alexander Graf:
We want to be able to reuse device drivers from 32bit code, so let's add definitions for all the dcache options that 32bit code has.
While at it, fix up the DCACHE_OFF configuration. That was setting the bits to declare a PTE a PTE and left the MAIR index bit at 0. Drop the useless bits and make the index explicit.
Signed-off-by: Alexander Graf agraf@suse.de
arch/arm/include/asm/system.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h index ac1173d..832c1db 100644 --- a/arch/arm/include/asm/system.h +++ b/arch/arm/include/asm/system.h @@ -26,8 +26,12 @@ u64 get_page_table_size(void); #define MMU_SECTION_SHIFT 21 #define MMU_SECTION_SIZE (1 << MMU_SECTION_SHIFT)
+/* These constants need to be synced to the MT_ types in asm/armv8/mmu.h */ enum dcache_option {
- DCACHE_OFF = 0x3,
- DCACHE_OFF = 0 << 2,
- DCACHE_WRITETHROUGH = 3 << 2,
- DCACHE_WRITEBACK = 4 << 2,
- DCACHE_WRITEALLOC = 4 << 2,
Is it intentional that these two have the same value?
Yes. We don't have any MAIR entry on AArch64 that defines writeback without alloc:
#define MT_DEVICE_NGNRNE 0 #define MT_DEVICE_NGNRE 1 #define MT_DEVICE_GRE 2 #define MT_NORMAL_NC 3 #define MT_NORMAL 4
#define MEMORY_ATTRIBUTES ((0x00 << (MT_DEVICE_NGNRNE * 8)) | \ (0x04 << (MT_DEVICE_NGNRE * 8)) | \ (0x0c << (MT_DEVICE_GRE * 8)) | \ (0x44 << (MT_NORMAL_NC * 8)) | \ (UL(0xff) << (MT_NORMAL * 8)))
So MAIR entries 0-4 are:
0: Device memory, Device-nGnRnE memory 1: Device memory, Device-nGnRE memory 2: Device memory, Device-GRE memory 3: Normal Memory, Outer Non-Cacheable, Inner Non-Cacheable 4: Normal Memory, Outer Write-back non-transient, Outer Read Allocate, Outer Write Allocate, Inner Write-back non-transient, Inner Read Allocate, Inner Write Allocate
But on armv7 we map memory as non-allocated by default. So I wanted to make sure we stay compatible with our RAM maps. Basically on armv8, "writeback" and "writealloc" both mean "cached RAM".
Alex