From 9a652bf4cfc943a5a59d23ea19c1efb202af5286 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Tue, 12 Aug 2025 21:49:20 -0400
Subject: kernel: vm: Add total system memory in vmstat

This commit introduces reporting of total system memory supported
through the vmstat subsystem

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/vm/vm_physmem.c | 12 ++++++++++++
 sys/vm/vm_stat.c    |  1 +
 2 files changed, 13 insertions(+)

(limited to 'sys/vm')

diff --git a/sys/vm/vm_physmem.c b/sys/vm/vm_physmem.c
index debec1f..b6e7347 100644
--- a/sys/vm/vm_physmem.c
+++ b/sys/vm/vm_physmem.c
@@ -40,6 +40,7 @@
 
 static size_t pages_free = 0;
 static size_t pages_used = 0;
+static size_t pages_total = 0;
 static size_t highest_frame_idx = 0;
 static size_t bitmap_size = 0;
 static size_t bitmap_free_start = 0;
@@ -64,6 +65,7 @@ physmem_populate_bitmap(void)
 
     for (size_t i = 0; i < resp->entry_count; ++i) {
         ent = resp->entries[i];
+        pages_total += ent->length / DEFAULT_PAGESIZE;
 
         if (ent->type != LIMINE_MEMMAP_USABLE) {
             /* This memory is not usable */
@@ -230,6 +232,16 @@ vm_mem_free(void)
     return (pages_free * DEFAULT_PAGESIZE) / BYTES_PER_MIB;
 }
 
+/*
+ * Return the total amount of memory supported
+ * by the machine.
+ */
+size_t
+vm_mem_total(void)
+{
+    return (pages_total * DEFAULT_PAGESIZE) / BYTES_PER_MIB;
+}
+
 void
 vm_physmem_init(void)
 {
diff --git a/sys/vm/vm_stat.c b/sys/vm/vm_stat.c
index 8cf2fe4..3e39047 100644
--- a/sys/vm/vm_stat.c
+++ b/sys/vm/vm_stat.c
@@ -71,6 +71,7 @@ vm_stat_get(struct vm_stat *vmstat)
 
     vmstat->mem_avail = vm_mem_free();
     vmstat->mem_used = vm_mem_used();
+    vmstat->mem_total = vm_mem_total();
     return 0;
 }
 
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