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[FREELDR]

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Patch by Brian Palmer:
Fix problems that could occur, when the BIOS returns memory regions that are not page aligned, by fixing up the bios memory map before using it.

svn path=/trunk/; revision=53797
This commit is contained in:
Timo Kreuzer 2011-09-21 23:02:24 +00:00
parent 994898f151
commit 7931e63ab8
1 changed files with 48 additions and 0 deletions
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48
reactos/boot/freeldr/freeldr/arcemul/mm.c
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@ -35,6 +35,49 @@ static const MEMORY_DESCRIPTOR_INT MemoryDescriptors[] =
#endif
};
static
VOID MmFixupSystemMemoryMap(PBIOS_MEMORY_MAP BiosMemoryMap, ULONG* MapCount)
{
int Index;
int Index2;
ULONGLONG BaseAddressOffset;
// Loop through each entry in the array
for (Index=0; Index<*MapCount; Index++)
{
// Correct all the addresses to be aligned on page boundaries
BaseAddressOffset = ROUND_UP(BiosMemoryMap[Index].BaseAddress, MM_PAGE_SIZE) - BiosMemoryMap[Index].BaseAddress;
BiosMemoryMap[Index].BaseAddress += BaseAddressOffset;
if (BiosMemoryMap[Index].Length < BaseAddressOffset)
{
BiosMemoryMap[Index].Length = 0;
}
else
{
BiosMemoryMap[Index].Length -= BaseAddressOffset;
}
BiosMemoryMap[Index].Length = ROUND_DOWN(BiosMemoryMap[Index].Length, MM_PAGE_SIZE);
// If the entry type isn't usable then remove
// it from the memory map (this will help reduce
// the size of our lookup table)
// If the length is less than a full page then
// get rid of it also.
if (BiosMemoryMap[Index].Type != BiosMemoryUsable ||
BiosMemoryMap[Index].Length < MM_PAGE_SIZE)
{
// Slide every entry after this down one
for (Index2=Index; Index2<(*MapCount - 1); Index2++)
{
BiosMemoryMap[Index2] = BiosMemoryMap[Index2 + 1];
}
(*MapCount)--;
Index--;
}
}
}
const MEMORY_DESCRIPTOR*
ArcGetMemoryDescriptor(const MEMORY_DESCRIPTOR* Current)
{
@ -58,6 +101,11 @@ ArcGetMemoryDescriptor(const MEMORY_DESCRIPTOR* Current)
sizeof(BiosMemoryMap) /
sizeof(BIOS_MEMORY_MAP));
//
// Fix entries that are not page aligned
//
MmFixupSystemMemoryMap(BiosMemoryMap, &BiosMemoryMapEntryCount);
//
// Copy the entries to our structure
//