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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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8
ArmPkg/Library/ArmLib/Arm/ArmLibSupport.asm
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@ -169,4 +169,12 @@
isb
bx lr
RVCT_ASM_EXPORT ArmGetPhysicalAddressBits
mrc p15, 0, r0, c0, c1, 4 ; MMFR0
and r0, r0, #0xf ; VMSA [3:0]
cmp r0, #5 ; >= 5 implies LPAE support
movlt r0, #32 ; 32 bits if no LPAE
movge r0, #40 ; 40 bits if LPAE
bx lr
END