Stealing memory from the mmap to init phys alloc

src/kernel.c

@@ -36,6 +36,7 @@
 #include "x86_64/mem.h"
 
 #include "bootboot.h"
+#include "ram.h"
 #include "pci.h"
 #include "std.h"
 #include "tar.h"
@@ -84,6 +85,7 @@ struct mem_range range_ptr[10];
  * Entry point, called by BOOTBOOT Loader *
  ******************************************/
 void _start() {
+	ram_init();
     /*** NOTE: this code runs on all cores in parallel ***/
 
     unsigned info[4];

src/ram.c

@@ -26,7 +26,6 @@ struct free_block {
 };
 
 struct ram_layer {
-	uint64_t total_blocks;
 	uint64_t first_free;
 	bitmap  *avail_bitmap;
 	bitmap  *frag_bitmap;
@@ -230,25 +229,10 @@ ram_free_frame(frame_addr frame)
 	free_block(frame.base);
 }
 
-static void
+// Find largest memory address available
-ram_alloc_datastructures()
-{
-#if 0
-	uint64_t neededBytes = 0;
-	
-	for (unsigned level = 0; level < ram_num_levels; level++) {
-		neededBytes += 2 * BITMAP_SIZE();
-	}
-
-	for (unsigned level = 0; level < ram_num_levels; level++) {
-	}
-#endif
-}
-
 static uint64_t
 ram_find_addr_limit(void)
 {
-	// Find largest memory address available
 	uint64_t addrLimit = 0;
 	MMapEnt *ment = &bootboot.mmap;
 	while ((uint64_t)ment < (uint64_t)&bootboot + bootboot.size) {
@@ -256,14 +240,44 @@ ram_find_addr_limit(void)
 		uint64_t length = MMapEnt_Size(ment); // in bytes
 		uint64_t end    = start + length;
 		if (addrLimit < end) addrLimit = end;
+		printf("%x %p %lu\n", MMapEnt_Type(ment), (void *)start, length);
 		ment++;
 	}
 	return addrLimit;
 }
 
+// Find largest contiguous free range
+static MMapEnt *
+ram_find_donor_range(void)
+{
+	MMapEnt *donor = NULL;
+	MMapEnt *ment = &bootboot.mmap;
+	for (; (uint64_t)ment < (uint64_t)&bootboot + bootboot.size; ment++) {
+		if (!MMapEnt_IsFree(ment)) continue;
+		if (!donor || MMapEnt_Size(donor) < MMapEnt_Size(ment)) {
+			donor = ment;
+		}
+	}
+	return donor;
+}
+
+static void *
+ram_steal_memory(MMapEnt *donor, size_t nbytes)
+{
+	nbytes = (nbytes + 15) & 0xFFFFFFFFFFFFFFF0ul;
+	printf("ram_steal_memory: donor size = %lu, nbytes = %lu\n", MMapEnt_Size(donor), nbytes);
+	ASSERT(MMapEnt_Size(donor) >= nbytes);
+	donor->size -= nbytes;
+	uint64_t addr = donor->ptr + donor->size;
+	return (void *)addr;
+}
+
 void
 ram_init(void)
 {
+	MMapEnt *donor = ram_find_donor_range();
+	ASSERT(donor != NULL);
+
 	// Calculate how many levels we need
 	uint64_t addrLimit = ram_find_addr_limit();
 	addrLimit = next_pow2(addrLimit);
@@ -272,8 +286,18 @@ ram_init(void)
 	}
 	ram_num_levels = __builtin_ffsl(addrLimit); // log2(addrLimit) + 1
 	ram_num_levels -= 12;
+	printf("addrLimit = %lu\n", addrLimit);
+	printf("ram_num_levels = %u\n", ram_num_levels);
 
-	ram_alloc_datastructures();
+	for (unsigned level = 0; level < ram_num_levels; level++) {
+		ram_layers[level].first_free = INVALID_FRAME_ADDR;
+		size_t bitmapSize = BITMAP_SIZE(1ul << (ram_num_levels - level - 1));
+		ram_layers[level].avail_bitmap = ram_steal_memory(donor, bitmapSize);
+		ram_layers[level].frag_bitmap  = ram_steal_memory(donor, bitmapSize);
+	}
+
+	// Realign donor range to page boundaries
+	donor->size &= UINT64_C(0xFFFFFFFFFFFFF00F);
 
 #if 0
 	// Mark all free memory blocks as available