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Kernel: Detect Aarch64 physical address bit width with CPU ID registers

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This commit is contained in:
konrad 2023-01-08 12:21:40 +01:00 • committed by Jelle Raaijmakers
parent 66c65f6e2c
commit 401fc6afae
4 changed files with 32 additions and 2 deletions
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26
Kernel/Arch/aarch64/CPUID.cpp
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@ -1478,4 +1478,30 @@ NonnullOwnPtr<KString> build_cpu_feature_names(CPUFeature::Type const& features)
return KString::must_create(builder.string_view());
}
u8 detect_physical_address_bit_width()
{
auto memory_model_feature_register_0 = Aarch64::ID_AA64MMFR0_EL1::read();
switch (memory_model_feature_register_0.PARange) {
case 0b0000:
return 32; // 4GB
case 0b0001:
return 36; // 64GB
case 0b0010:
return 40; // 1TB
case 0b0011:
return 42; // 4TB
case 0b0100:
return 44; // 16TB
case 0b0101:
return 48; // 256TB
case 0b0110:
return 52; // 4PB (applies for FEAT_LPA or FEAT_LPA2)
case 0b0111:
return 56; // 64PB (applies for FEAT_D128)
default:
VERIFY_NOT_REACHED();
}
}
}

2
Kernel/Arch/aarch64/CPUID.h
View file

@ -277,4 +277,6 @@ StringView cpu_feature_to_name(CPUFeature::Type const&);
StringView cpu_feature_to_description(CPUFeature::Type const&);
NonnullOwnPtr<KString> build_cpu_feature_names(CPUFeature::Type const&);
u8 detect_physical_address_bit_width();
}

2
Kernel/Arch/aarch64/Processor.cpp
View file

@ -33,6 +33,7 @@ void Processor::install(u32 cpu)
VERIFY(g_current_processor == nullptr);
m_cpu = cpu;
m_features = detect_cpu_features();
m_physical_address_bit_width = detect_physical_address_bit_width();
initialize_exceptions(cpu);
@ -42,6 +43,7 @@ void Processor::install(u32 cpu)
void Processor::initialize()
{
dmesgln("CPU[{}]: Supports {}", m_cpu, build_cpu_feature_names(m_features));
dmesgln("CPU[{}]: Physical address bit width: {}", m_cpu, m_physical_address_bit_width);
}
[[noreturn]] void Processor::halt()

4
Kernel/Arch/aarch64/Processor.h
View file

@ -84,8 +84,7 @@ public:
ALWAYS_INLINE u8 physical_address_bit_width() const
{
TODO_AARCH64();
return 0;
return m_physical_address_bit_width;
}
ALWAYS_INLINE u8 virtual_address_bit_width() const
@ -286,6 +285,7 @@ private:
u32 m_cpu;
CPUFeature::Type m_features;
u8 m_physical_address_bit_width;
Thread* m_current_thread;
Thread* m_idle_thread;