From 5e425e4e9ecbe28ae88472b311767f3b3fd9c984 Mon Sep 17 00:00:00 2001
From: lizzie <lizzie@eden-emu.dev>
Date: Sun, 26 Apr 2026 09:39:11 +0000
Subject: [PATCH] [ports, freebsd] use shm_create_largepage(3) with a DEFAULT
 allocation to exploit defragmented RAM situations

Signed-off-by: lizzie <lizzie@eden-emu.dev>
---
 src/common/host_memory.cpp | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/common/host_memory.cpp b/src/common/host_memory.cpp
index 75a9da80e9..975b5c407b 100644
--- a/src/common/host_memory.cpp
+++ b/src/common/host_memory.cpp
@@ -22,6 +22,7 @@
 #include <sys/mman.h>
 #include <unistd.h>
 #include "common/scope_exit.h"
+#include "common/literals.h"
 
 #if defined(__linux__)
 #include <sys/random.h>
@@ -526,7 +527,30 @@ public:
 #elif defined(__OpenBSD__)
         fd = shm_open_anon(O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW, 0600);
 #elif defined(__FreeBSD__)
-        fd = shm_open(SHM_ANON, O_RDWR, 0600);
+        int n_page_sizes = getpagesizes(nullptr, 0);
+        if (n_page_sizes > 0) {
+            std::vector<size_t> page_sizes(n_page_sizes);
+            if (getpagesizes(page_sizes.data(), n_page_sizes) > 0) {
+                size_t max_size = page_sizes[0];
+                size_t max_index = 0;
+                for (size_t i = 0; i < page_sizes.size(); ++i) {
+                    using namespace Common::Literals;
+                    if (page_sizes[i] <= 4_GiB) {
+                        max_size = (std::max)(max_size, page_sizes[i]);
+                        max_index = i;
+                    }
+                }
+                LOG_WARNING(Common_Memory, "using largepage of size {} #{}", max_size, max_index);
+                // Do not use SHM_LARGEPAGE_ALLOC_HARD, yknow what will happen when you do?
+                // the entire Eden process will hang for eternity! that's what will happen
+                // Want to fuck around and find out? Go ahead, I tempt you change the "default" to "hard"
+                fd = shm_create_largepage(SHM_ANON, O_RDWR, max_index, SHM_LARGEPAGE_ALLOC_DEFAULT, 0600);
+            }
+        }
+        if (fd < 0) {
+            LOG_WARNING(Common_Memory, "unable to force largepage: {}", strerror(errno));
+            fd = shm_open(SHM_ANON, O_RDWR, 0600);
+        }
 #elif defined(__APPLE__) || defined(__managarm__)
         // macOS doesn't have memfd_create, use anonymous temporary file
         char template_path[] = "/tmp/eden_mem_XXXXXX";
@@ -558,7 +582,12 @@ public:
                 close(fd);
             }
         } else {
-            backing_base = static_cast<u8*>(mmap(nullptr, backing_size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_NOCORE, fd, 0));
+            int map_flags =MAP_SHARED | MAP_NOCORE;
+#ifdef __FreeBSD__
+            // Prevent dirty tracking of memfd
+            map_flags |= MAP_NOSYNC;
+#endif
+            backing_base = static_cast<u8*>(mmap(nullptr, backing_size, PROT_READ | PROT_WRITE, map_flags, fd, 0));
         }
         if (backing_base == MAP_FAILED) {
             LOG_CRITICAL(HW_Memory, "mmap failed: {}", strerror(errno));