/////////////////////////////////////
// PUBLIC METHODS
/////////////////////////////////////
//
// Initialize() must be called during OS boot *BEFORE* paging
// is enabled, so that physical memory can be accessed
// directly. We consult the system's memory map to pick a
// range of memory where we can situate the physical page
// table, and initialize it.
//
// the reserveSize argument specifies how much physical
// memory to set aside and return a PhysicalAddress to.
// This is used by the MemoryManager to reserve an area
// of contiguous physical memory for use in I/O operations.
//
// After Initialize()ation, the PhysicalPages module
// assumes that its page table will be identity-mapped
// into the kernel's virtual memory space.
//
internal static unsafe PhysicalAddress Initialize(ulong reserveSize)
{
Platform p = Platform.ThePlatform;
UIntPtr lowerAddress = UIntPtr.Zero;
UIntPtr upperAddress = UIntPtr.Zero;
// NB: our initialization is currently naive; we
// set up a table to describe all of physical memory,
// even though there are holes in it for reserved
// memory that we will never be able to use.
// This makes indexing much easier, though.
InitializeLock();
// Retrieve the highest RAM address
MemoryManager.PhysicalMemoryLimits(out lowerAddress, out upperAddress);
addressLimit = (ulong)upperAddress;
DebugStub.WriteLine("Highest usable RAM address is 0x{0:x8}",
__arglist(addressLimit));
// How much room do we need for the pageblock table?
numBlocks = GetNumBlocks(addressLimit);
ulong requiredSpace = (ulong)numBlocks * (ulong)sizeof(PageBlock);
// Now we need to find a location in physical memory
// where we can stick the physical pageblock table.
ulong startAddr = LowerRAMBlackout;
if (p.BootAllocatedMemorySize != 0) {
if (startAddr > p.BootAllocatedMemory &&
startAddr < p.BootAllocatedMemory + p.BootAllocatedMemorySize) {
startAddr = (ulong)p.BootAllocatedMemory + (ulong)p.BootAllocatedMemorySize;
}
}
ulong physLocation = FindFreeBlockInSMAP(startAddr, requiredSpace);
if (physLocation == 0) {
// Failed to find a spot to park the physical page
// table. This is fatal!
Kernel.Panic("Couldn't find enough room to initialize hardware page table");
}
// Initialize all the descriptor blocks as "free" (zeroed)
physTable = (PageBlock*)physLocation;
tableSize = requiredSpace;
freeList = 0; // First descriptor
for (uint i = 0; i < numBlocks; i++) {
PageBlock* thisBlock = GetBlock(i);
thisBlock->Initialize();
thisBlock->prevIdx = (i == 0) ? PageBlock.Sentinel : i - 1;
thisBlock->nextIdx = (i == numBlocks - 1) ? PageBlock.Sentinel : i + 1;
}
// Mark the blackout area of low physical memory as used
MarkRangeUsed(0, startAddr - 1);
// Now mark the range of physical pages occupied by the
// hardware table itself as being used!
MarkRangeUsed((ulong)physTable, requiredSpace);
// Mark any non-Free areas (according to SMAP) as in use
SMAPINFO* smap = p.Smap;
for (uint i = 0; i < p.SmapCount; i++) {
if ((smap[i].type != (ulong)SMAPINFO.AddressType.Free) &&
((smap[i].addr + smap[i].size) > startAddr) &&
(smap[i].addr < addressLimit)) {
ulong unaccountedStart, unaccountedLength;
if (smap[i].addr >= startAddr) {
unaccountedStart = smap[i].addr;
unaccountedLength = smap[i].size;
}
else {
// Part of this memory window is already accounted for
unaccountedStart = startAddr;
unaccountedLength = smap[i].size - (startAddr - smap[i].addr);
}
MarkRangeUsed(unaccountedStart, unaccountedLength);
}
}
// Mark out all the Platform special regions as busy
if (p.MiniDumpLimit != 0) {
ulong miniDumpSize = (ulong)p.MiniDumpLimit - (ulong)p.MiniDumpBase;
MarkRangeUsed((ulong)p.MiniDumpBase,
MemoryManager.PagePad(miniDumpSize));
}
if (p.KernelDllSize != 0) {
MarkRangeUsed((ulong)p.KernelDllBase,
MemoryManager.PagePad((ulong)p.KernelDllSize));
}
if (p.BootAllocatedMemorySize != 0) {
MarkRangeUsed((ulong)p.BootAllocatedMemory,
MemoryManager.PagePad((ulong)p.BootAllocatedMemorySize));
}
// Last step: find an available area to situate the caller's
// requested reserve-block, if any.
PhysicalAddress reservedPtr = PhysicalAddress.Null;
if (reserveSize != 0) {
reservedPtr = new PhysicalAddress(
FindFreeBlockInSMAP(
MemoryManager.PagePad((ulong)physTable + tableSize),
reserveSize));
if (reservedPtr == PhysicalAddress.Null) {
Kernel.Panic("Couldn't find enough physically contiguous memory to reserve");
}
if (reservedPtr.Value + reserveSize > 0xFFFFFF) {
Kernel.Panic("Couldn't find enough physically contiguous memory below 0xFFFFFF for I/O memory");
}
}
// Mark the reserved block as used. It's up to the caller
// to administer its use.
MarkRangeUsed(reservedPtr.Value, reserveSize);
CheckConsistency();
DebugStub.WriteLine("PhysicalPages initialized at 0x{0:x8} - 0x{1:x8} with {2} physical pages available.",
__arglist(reservedPtr.Value,
reservedPtr.Value + reserveSize,
GetFreePageCount()));
return reservedPtr;
}