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Complete HEAPMNG page-map coverage and high-address coalescing #164

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Complete HEAPMNG page-map coverage and high-address coalescing #164

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ef2496f
Complete HEAPMNG full-range bookkeeping
zhanghm18GIT Jul 26, 2026
a402f34
Document HEAPMNG full-range bookkeeping
zhanghm18GIT Jul 26, 2026
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2 changes: 1 addition & 1 deletion changelog.md
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Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,7 @@ These don't matter except for other assembly patches

## Improvements

- Allows to use 4GB on x64
- Complete HEAPMNG page-map coverage and enable free-region coalescing across the 3-4 GiB range on x64.

- hooks/HFix4GB.cpp

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11 changes: 9 additions & 2 deletions hooks/HFix4GB.cpp
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@@ -1,6 +1,8 @@
asm(
// Allocate one 4-byte map entry for every 4 KiB page in the complete
// 32-bit virtual address space: 0x100000 entries * 4 = 0x400000 bytes.
".section h0; .set h0,0x957E35;"
"PUSH 0x3FF000;"
"PUSH 0x400000;"

".section h1; .set h1,0x915A92;"
"ADD EAX,EAX;"
Expand All @@ -11,4 +13,9 @@ asm(

".section h2; .set h2,0x915B05;"
"JMP .-0x73;"
);

// Keep 0x100000 as the one-past-end page index while allowing free
// regions in the 3-4 GiB range to coalesce with a right neighbour.
".section h3; .set h3,0x958107;"
"CMP EAX,0x100000;"
);