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ArmPlatformPkg/FVP: map motherboard VRAM as uncached memory

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The VRAM of the PL111 on the FVP Base/Foundation models is described as
device memory rather than uncached memory, which is not an accurate
description of the nature of the region (i.e., a framebuffer), and may
result in problems when using accelerated string routines to access the
region, since this may legally involve unaligned accesses or DC ZVA
instructions, which are not allowed on device mappings.

So split of the 8 MB VRAM region into a separate region, and map it using
memory attributes.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
Tested-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
This commit is contained in:
Ard Biesheuvel
2017-04-06 14:05:12 +01:00
parent 7c410b3d41
commit 1344c8c605
2 changed files with 18 additions and 7 deletions
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14
ArmPlatformPkg/ArmVExpressPkg/Library/ArmVExpressLibRTSM/RTSMMem.c
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@@ -21,7 +21,7 @@
#include <ArmPlatform.h>
// Number of Virtual Memory Map Descriptors
#define MAX_VIRTUAL_MEMORY_MAP_DESCRIPTORS 8
#define MAX_VIRTUAL_MEMORY_MAP_DESCRIPTORS 9
// DDR attributes
#define DDR_ATTRIBUTES_CACHED ARM_MEMORY_REGION_ATTRIBUTE_WRITE_BACK
@@ -130,6 +130,18 @@ ArmPlatformGetVirtualMemoryMap (
VirtualMemoryTable[Index].Length = 2 * ARM_VE_SMB_PERIPH_SZ;
VirtualMemoryTable[Index].Attributes = ARM_MEMORY_REGION_ATTRIBUTE_DEVICE;
// VRAM
VirtualMemoryTable[++Index].PhysicalBase = PL111_CLCD_VRAM_MOTHERBOARD_BASE;
VirtualMemoryTable[Index].VirtualBase = PL111_CLCD_VRAM_MOTHERBOARD_BASE;
VirtualMemoryTable[Index].Length = PL111_CLCD_VRAM_MOTHERBOARD_SIZE;
//
// Map the VRAM region as Normal Non-Cacheable memory and not device memory,
// so that we can use the accelerated string routines that may use unaligned
// accesses or DC ZVA instructions. The enum identifier is slightly awkward
// here, but it maps to a memory type that allows buffering and reordering.
//
VirtualMemoryTable[Index].Attributes = ARM_MEMORY_REGION_ATTRIBUTE_UNCACHED_UNBUFFERED;
// Map sparse memory region if present
if (HasSparseMemory) {
VirtualMemoryTable[++Index].PhysicalBase = SparseMemoryBase;