Use a freelist for GDT entries.

Tweak the kmalloc space layout a bit. Get the spawn stress test up
and running again.

1 files changed, 17 insertions, 6 deletions

diff --git a/Kernel/i386.cpp b/Kernel/i386.cpp
index 0a778ca9cd..9ebdd95c19 100644
--- a/Kernel/i386.cpp
+++ b/Kernel/i386.cpp
@@ -20,15 +20,20 @@ static Descriptor* s_gdt;
 
 static IRQHandler** s_irqHandler;
 
+static Vector<word, KmallocEternalAllocator>* s_gdt_freelist;
+
 static WORD s_gdtLength;
 
-WORD allocateGDTEntry()
+word gdt_alloc_entry()
 {
-    // FIXME: This should not grow indefinitely.
-    ASSERT(s_gdtLength < 256);
-    WORD newGDTEntry = s_gdtLength * 8;
-    s_gdtLength++;
-    return newGDTEntry;
+    ASSERT(s_gdt_freelist);
+    ASSERT(!s_gdt_freelist->isEmpty());
+    return s_gdt_freelist->takeLast();
+}
+
+void gdt_free_entry(word entry)
+{
+    s_gdt_freelist->append(entry);
 }
 
 extern "C" void handleIRQ();
@@ -310,6 +315,12 @@ void gdt_init()
     s_gdt = static_cast<Descriptor*>(kmalloc_eternal(sizeof(Descriptor) * 256));
     s_gdtLength = 5;
 
+    s_gdt_freelist = new Vector<word, KmallocEternalAllocator>();
+    s_gdt_freelist->ensureCapacity(256);
+    for (size_t i = s_gdtLength; i < 256; ++i)
+        s_gdt_freelist->uncheckedAppend(i * 8);
+
+    s_gdtLength = 256;
     s_gdtr.address = s_gdt;
     s_gdtr.size = (s_gdtLength * 8) - 1;