ptos: mm: Add physical memory groundwork

Signed-off-by: Chloe M <chloe@mensia.org>
2026-07-10 18:26:29 -04:00
parent 5026a758ec
commit 27b9d726ff
4 changed files with 91 additions and 0 deletions
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Physical memory management
+ * Author:      Chloe M.
+ */
+
+#include <mm/pm.h>
+#include <ke/bpal.h>
+#include <ex/trace.h>
+
+#define DTRACE(Fmt, ...) \
+    TRACE("[ PM ]: " Fmt, ##__VA_ARGS__)
+
+/* Safe macro to get region string */
+#define PM_REGION(TYPE)                 \
+    ((TYPE) >= NELEM(PmRegionTable))    \
+        ? "bad type"                    \
+        : PmRegionTable[(TYPE)]
+
+/*
+ * Table of known memory regions
+ */
+static const CHAR *PmRegionTable[] = {
+    [MEMORY_USABLE]         = "available",
+    [MEMORY_RESERVED]       = "reserved",
+    [MEMORY_ACPI_RECLAIM]   = "acpi reclaimable",
+    [MEMORY_ACPI_NVS]       = "acpi nv-sleep",
+    [MEMORY_BAD]            = "bad",
+    [MEMORY_BOOTLOADER]     = "bootloader",
+    [MEMORY_KERNEL]         = "system",
+    [MEMORY_FRAMEBUFFER]    = "vram",
+    [MEMORY_ACPI_TABLES]    = "acpi tables"
+};
+
+/*
+ * Probe physical memory for usable regions and list
+ * installed memory.
+ */
+static VOID
+PmProbe(VOID)
+{
+    PT_STATUS Status;
+    BPAL_HANDLE BpalHandle;
+    MEMMAP_ENTRY Entry;
+    UPTR Start, End;
+    USIZE Index;
+
+    /*
+     * We obtain memory map entries from the BPAL layer as it is provided
+     * by the bootloader which got it from firmware.
+     */
+    KeBpalGetHandle(&BpalHandle);
+
+    /* Iterate each memory entry */
+    for (Index = 0;; ++Index) {
+        Status = BpalHandle.MemEntryIdx(Index, &Entry);
+
+        /* Are we out of entries to fetch? */
+        if (PT_ERROR(Status)) {
+            break;
+        }
+
+        Start = Entry.Base;
+        End = Start + Entry.Length;
+        DTRACE(
+            "%p - %p : %s\n",
+            Start,
+            End,
+            PM_REGION(Entry.Type)
+        );
+    }
+}
+
+VOID
+MmPmInit(VOID)
+{
+    DTRACE("probing physical memory...\n");
+    PmProbe();
+}