kern: vm: Add initial physical memory management

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 165 insertions, 0 deletions

diff --git a/sys/inc/vm/phys.h b/sys/inc/vm/phys.h
new file mode 100644
index 0000000..805759a
--- /dev/null
+++ b/sys/inc/vm/phys.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPKERNE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LKERNS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * PKERNSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _VM_PHYS_H_
+#define _VM_PHYS_H_
+
+#include <sys/types.h>
+
+void vm_phys_init(void);
+
+#endif  /* !_VM_PHYS_H_ */
diff --git a/sys/kern/kern_init.c b/sys/kern/kern_init.c
index bba8cea..74e17c4 100644
--- a/sys/kern/kern_init.c
+++ b/sys/kern/kern_init.c
@@ -30,6 +30,7 @@
 #include <sys/types.h>
 #include <dev/cons/cons.h>
 #include <os/trace.h>
+#include <vm/phys.h>
 
 struct console g_bootcons;
 void kmain(void);
@@ -39,4 +40,5 @@ kmain(void)
 {
     console_reset(&g_bootcons);
     trace("bootcons: console online\n");
+    vm_phys_init();
 }
diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
new file mode 100644
index 0000000..dd94014
--- /dev/null
+++ b/sys/vm/vm_phys.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPKERNE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LKERNS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * PKERNSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <kern/panic.h>
+#include <os/trace.h>
+#include <vm/phys.h>
+#include <lib/limine.h>
+
+#define dtrace(fmt, ...) trace("phys: " fmt, ##__VA_ARGS__)
+
+#define MEM_GIB 0x40000000
+#define MEM_MIB 0x100000
+
+/* Aliases for portability */
+#define MEM_USABLE              (LIMINE_MEMMAP_USABLE)
+#define MEM_RESERVED            (LIMINE_MEMMAP_RESERVED)
+#define MEM_ACPI_RECLAIMABLE    (LIMINE_MEMMAP_ACPI_RECLAIMABLE)
+#define MEM_ACPI_NVS            (LIMINE_MEMMAP_ACPI_NVS)
+#define MEM_BAD                 (LIMINE_MEMMAP_BAD_MEMORY)
+#define MEM_BOOTLOADER          (LIMINE_MEMMAP_BOOTLOADER_RECLAIMABLE)
+#define MEM_KERNEL              (LIMINE_MEMMAP_KERNEL_AND_MODULES)
+#define MEM_FRAMEBUFFER         (LIMINE_MEMMAP_FRAMEBUFFER)
+
+#define MEM_ENTRY(INDEX) (memmap_resp->entries[(INDEX)])
+#define MEM_ENTRY_COUNT  (memmap_resp->entry_count)
+
+typedef struct limine_memmap_entry mementry_t;
+
+/* Memory statistics */
+static size_t total_mem = 0;
+static size_t free_mem = 0;
+static size_t reserved_mem = 0;
+static uintptr_t highest_usable = 0;
+
+/*
+ * Request a memor map from the bootloader
+ */
+static struct limine_memmap_response *memmap_resp;
+static volatile struct limine_memmap_request memmap_req = {
+    .id = LIMINE_MEMMAP_REQUEST,
+    .revision = 0
+};
+
+/*
+ * Print memory size related stats
+ */
+static void
+vm_printstat(const char *name, size_t size)
+{
+    if (size >= MEM_GIB) {
+        dtrace("%s %d GiB\n", name, size / MEM_GIB);
+    } else {
+        dtrace("%s %d MiB\n", name, size / MEM_MIB);
+    }
+}
+
+/*
+ * Probe for usable memory
+ */
+static void
+vm_probe(void)
+{
+    mementry_t *entry;
+
+    for (size_t i = 0; i < MEM_ENTRY_COUNT; ++i) {
+        entry = MEM_ENTRY(i);
+
+        if (entry->type != MEM_USABLE) {
+            total_mem += entry->length;
+            reserved_mem += entry->length;
+            continue;
+        }
+
+        total_mem += entry->length;
+        free_mem += entry->length;
+
+        if ((entry->base + entry->length) > highest_usable) {
+            highest_usable = entry->base + entry->length;
+        }
+    }
+
+    vm_printstat("memory installed", total_mem);
+    vm_printstat("memory usable", free_mem);
+    vm_printstat("memory reserved", reserved_mem);
+    dtrace("usable top @ %p\n", highest_usable);
+}
+
+void
+vm_phys_init(void)
+{
+    memmap_resp = memmap_req.response;
+    if (__unlikely(memmap_resp == NULL)) {
+        panic("vm: unable to get memory map\n");
+    }
+
+    dtrace("checking memory resources...\n");
+    vm_probe();
+}