start writing documentation

1 files changed, 32 insertions, 0 deletions

diff --git a/arch/riscv64/include/vmem.h b/arch/riscv64/include/vmem.h
index a557513..fc3df00 100644
--- a/arch/riscv64/include/vmem.h
+++ b/arch/riscv64/include/vmem.h
@@ -11,28 +11,60 @@
 #include <apos/types.h>
 #include <apos/attrs.h>
 
+/**
+ * Number of entries in one page table, depends on if we're running riscv32 or
+ * riscv64.
+ */
 #if __riscv_xlen == 64
+ /** When running riscv64, each page table has 512 8byte entries. */
 #define RISCV_NUM_LEAVES 512
 #else
+ /** When running riscv32, each page table has 1024 4byte entries. */
 #define RISCV_NUM_LEAVES 1024
 #endif
 
+/** Page is active. */
 #define VM_V (1 << 0)
+
+/** Page is readable. */
 #define VM_R (1 << 1)
+
+/** Page is writable. */
 #define VM_W (1 << 2)
+
+/** Page is executable. */
 #define VM_X (1 << 3)
+
+/** Page is user-accessible. */
 #define VM_U (1 << 4)
+
+/** Page is global. */
 #define VM_G (1 << 5)
+
+/** Page has been accessed. */
 #define VM_A (1 << 6)
+
+/** Page is dirty. */
 #define VM_D (1 << 7)
 
+/** Memory mode of cpu. Currently only Sv39 is supported. */
 enum mm_mode {
+	/** 48bit effective addresses on 64bit systems. */
 	Sv48,
+	/** 39bit effective addresses on 64bit systems. */
 	Sv39,
+	/** 32bit effective addresses on 32bit systems. */
 	Sv32,
 };
 
+/**
+ * Virtual memory.
+ *
+ * On riscv, all page tables are luckily identical, so we can
+ * use this without much trickery.
+ */
 struct vmem {
+	/** RISCV_NUM_LEAVES pointers to other page tables. */
 	struct vmem *leaf[RISCV_NUM_LEAVES];
 };