From ac6e6f3ec1fb79ea4e526225b2d0247f8c1cafa1 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Sat, 11 Apr 2026 08:29:10 +0300
Subject: [PATCH] Kernel: Add ioctl to sync rectangular areas in framebuffer

msync is not really the best API for framebuffer synchronization
---
 .../include/kernel/Device/FramebufferDevice.h |  2 ++
 kernel/kernel/Device/FramebufferDevice.cpp    | 21 +++++++++++++++++++
 userspace/libraries/LibC/include/sys/ioctl.h  |  9 ++++++++
 3 files changed, 32 insertions(+)

diff --git a/kernel/include/kernel/Device/FramebufferDevice.h b/kernel/include/kernel/Device/FramebufferDevice.h
index 8a095c40..f298aaca 100644
--- a/kernel/include/kernel/Device/FramebufferDevice.h
+++ b/kernel/include/kernel/Device/FramebufferDevice.h
@@ -37,6 +37,8 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override;
 
+		BAN::ErrorOr<long> ioctl_impl(int cmd, void* arg) override;
+
 		virtual bool can_read_impl() const override { return true; }
 		virtual bool can_write_impl() const override { return true; }
 		virtual bool has_error_impl() const override { return false; }
diff --git a/kernel/kernel/Device/FramebufferDevice.cpp b/kernel/kernel/Device/FramebufferDevice.cpp
index 071a343d..37e16215 100644
--- a/kernel/kernel/Device/FramebufferDevice.cpp
+++ b/kernel/kernel/Device/FramebufferDevice.cpp
@@ -6,6 +6,7 @@
 #include <kernel/Terminal/FramebufferTerminal.h>
 
 #include <sys/framebuffer.h>
+#include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <sys/sysmacros.h>
 
@@ -133,6 +134,26 @@ namespace Kernel
 		return bytes_to_copy;
 	}
 
+	BAN::ErrorOr<long> FramebufferDevice::ioctl_impl(int cmd, void* arg)
+	{
+		switch (cmd)
+		{
+			case FB_MSYNC_RECTANGLE:
+			{
+				auto& rectangle = *static_cast<fb_msync_region*>(arg);
+				sync_pixels_rectangle(
+					rectangle.min_x,
+					rectangle.min_y,
+					rectangle.max_x - rectangle.min_x,
+					rectangle.max_y - rectangle.min_y
+				);
+				return 0;
+			}
+		}
+
+		return CharacterDevice::ioctl(cmd, arg);
+	}
+
 	uint32_t FramebufferDevice::get_pixel(uint32_t x, uint32_t y) const
 	{
 		ASSERT(x < m_width && y < m_height);
diff --git a/userspace/libraries/LibC/include/sys/ioctl.h b/userspace/libraries/LibC/include/sys/ioctl.h
index d1842427..0a6366c3 100644
--- a/userspace/libraries/LibC/include/sys/ioctl.h
+++ b/userspace/libraries/LibC/include/sys/ioctl.h
@@ -74,6 +74,15 @@ struct snd_volume_info
 #define JOYSTICK_GET_RUMBLE 82 /* get controller rumble strength to uint8_t argument */
 #define JOYSTICK_SET_RUMBLE 83 /* set controller rumble strength to uint8_t argument */
 
+struct fb_msync_region
+{
+	uint32_t min_x;
+	uint32_t min_y;
+	uint32_t max_x;
+	uint32_t max_y;
+};
+#define FB_MSYNC_RECTANGLE 90 /* msync a rectangular area in mmap'd framebuffer device */
+
 int ioctl(int, int, ...);
 
 __END_DECLS