58 lines
1.7 KiB
C++
58 lines
1.7 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2012, 2013.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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x86-family/pat.cpp
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Tests whether PAT is available and initializes it.
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*******************************************************************************/
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#include <msr.h>
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#include <stdint.h>
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#include <sortix/kernel/cpuid.h>
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#include <sortix/kernel/kernel.h>
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#include <sortix/kernel/pat.h>
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#include "memorymanagement.h"
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namespace Sortix {
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static const uint32_t bit_PAT = 0x00010000U;
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bool IsPATSupported()
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{
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if ( !IsCPUIdSupported() )
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return false;
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uint32_t eax, ebx, ecx, edx;
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cpuid(1, eax, ebx, ecx, edx);
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uint32_t features = edx;
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return features & bit_PAT;
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}
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void InitializePAT()
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{
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using namespace Sortix::Memory;
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const uint32_t LOW = PA[0] << 0 | PA[1] << 8 | PA[2] << 16 | PA[3] << 24;
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const uint32_t HIGH = PA[4] << 0 | PA[5] << 8 | PA[6] << 16 | PA[7] << 24;
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const int PAT_REG = 0x0277;
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wrmsr(PAT_REG, (uint64_t) LOW << 0 | (uint64_t) HIGH << 32);
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}
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} // namespace Sortix
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