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ArmPkg/ArmLib: add support for reading the max physical address space size

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Add a helper function that returns the maximum physical address space
size as supported by the current CPU.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
This commit is contained in:
Ard Biesheuvel
2018-11-23 13:14:27 +01:00
parent 82379bf660
commit 95d04ebca8
4 changed files with 39 additions and 0 deletions
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17
ArmPkg/Library/ArmLib/AArch64/ArmLibSupport.S
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@@ -196,4 +196,21 @@ ASM_FUNC(ArmWriteSctlr)
3:msr sctlr_el3, x0
4:ret
ASM_FUNC(ArmGetPhysicalAddressBits)
mrs x0, id_aa64mmfr0_el1
adr x1, .LPARanges
and x0, x0, #0xf
ldrb w0, [x1, x0]
ret
//
// Bits 0..3 of the AA64MFR0_EL1 system register encode the size of the
// physical address space support on this CPU:
// 0 == 32 bits, 1 == 36 bits, etc etc
// 7 and up are reserved
//
.LPARanges:
.byte 32, 36, 40, 42, 44, 48, 52, 0
.byte 0, 0, 0, 0, 0, 0, 0, 0
ASM_FUNCTION_REMOVE_IF_UNREFERENCED