Allow bootloader bitmap framebuffer modesetting.

kernel/.gitignore

@@ -8,3 +8,4 @@
 *.out
 kb/default-kblayout
 kb/default-kblayout.h
+vgafont.h

kernel/Makefile

@@ -200,7 +200,10 @@ endif
 kb/default-kblayout.h: kb/default-kblayout
 	carray -cgis --uint8_t --guard=SORTIX_KB_DEFAULT_KBLAYOUT_H --identifier=default_kblayout $< -o $@
 
-*.cpp */*.cpp */*/*.cpp: | kb/default-kblayout.h
+vgafont.h: vgafont.f16
+	carray -gis --uint8_t --guard=VGAFONT_H --identifier=vgafont $< -o $@
+
+*.cpp */*.cpp */*/*.cpp: | kb/default-kblayout.h vgafont.h
 
 %.o: %.cpp
 	$(CXX) -c $< -o $@ $(CPPFLAGS) $(CXXFLAGS)
@@ -213,6 +216,7 @@ clean:
 	rm -f *.bin *.out *.tmp
 	rm -f *.o */*.o */*/*.o
 	rm -f kb/default-kblayout kb/default-kblayout.h
+	rm -f vgafont.h
 
 # Installation into sysroot
 install: install-headers install-kernel

kernel/include/sortix/kernel/log.h

@@ -42,6 +42,12 @@ class TextBufferHandle;
 namespace Sortix {
 namespace Log {
 
+extern uint8_t* fallback_framebuffer;
+extern size_t fallback_framebuffer_bpp;
+extern size_t fallback_framebuffer_pitch;
+extern size_t fallback_framebuffer_width;
+extern size_t fallback_framebuffer_height;
+
 extern TextBufferHandle* device_textbufhandle;
 extern size_t (*device_callback)(void*, const char*, size_t);
 extern size_t (*device_width)(void*);

kernel/include/sortix/kernel/textbuffer.h

@@ -87,6 +87,7 @@ public:
 	virtual void SetCursorEnabled(bool enablecursor) = 0;
 	virtual TextPos GetCursorPos() const = 0;
 	virtual void SetCursorPos(TextPos cursorpos) = 0;
+	virtual void SpawnThreads() = 0;
 	virtual bool EmergencyIsImpaired() = 0;
 	virtual bool EmergencyRecoup() = 0;
 	virtual void EmergencyReset() = 0;

kernel/kernel.cpp

@@ -483,6 +483,15 @@ static void BootThread(void* /*user*/)
 	// Hello, threaded world! You can now regard the kernel as a multi-threaded
 	// process with super-root access to the system. Before we boot the full
 	// system we need to start some worker threads.
+
+	// Spawn worker threads to asyncronously draw the console thread.
+	TextBuffer* textbuf = Log::device_textbufhandle->Acquire();
+	if ( textbuf )
+	{
+		textbuf->SpawnThreads();
+		Log::device_textbufhandle->Release(textbuf);
+	}
+
 	// Let's create the interrupt worker thread that executes additional work
 	// requested by interrupt handlers, where such work isn't safe.
 	Thread* interruptworker = RunKernelThread(Interrupt::WorkerThread, NULL);

kernel/lfbtextbuffer.cpp

@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2012, 2013, 2014.
+    Copyright(C) Jonas 'Sortie' Termansen 2012, 2013, 2014, 2015.
 
     This file is part of Sortix.
 
@@ -123,13 +123,12 @@ LFBTextBuffer* CreateLFBTextBuffer(uint8_t* lfb, uint32_t lfbformat,
 		memset(lfb + scansize * y, 0, lfbformat/8UL * xres);
 	ret->emergency_state = false;
 
-	ret->queue_thread = true;
+	if ( !kernel_process )
+		return ret;
+
+	ret->queue_thread = true; // Visible to new thread.
 	if ( !RunKernelThread(kernel_process, LFBTextBuffer__RenderThread, ret) )
-	{
 		ret->queue_thread = false;
-		delete ret;
-		return NULL;
-	}
 
 	return ret;
 
@@ -147,6 +146,16 @@ cleanup_done:
 	return NULL;
 }
 
+void LFBTextBuffer::SpawnThreads()
+{
+	if ( queue_thread )
+		return;
+	Process* kernel_process = Scheduler::GetKernelProcess();
+	queue_thread = true; // Visible to new thread.
+	if ( !RunKernelThread(kernel_process, LFBTextBuffer__RenderThread, this) )
+		queue_thread = false;
+}
+
 LFBTextBuffer::LFBTextBuffer()
 {
 }
@@ -315,7 +324,7 @@ void LFBTextBuffer::RenderRange(TextPos from, TextPos to)
 
 void LFBTextBuffer::IssueCommand(TextBufferCmd* cmd)
 {
-	if ( emergency_state )
+	if ( !queue_thread || emergency_state )
 	{
 		bool exit_requested = false;
 		bool sync_requested = false;
@@ -337,7 +346,7 @@ void LFBTextBuffer::IssueCommand(TextBufferCmd* cmd)
 
 void LFBTextBuffer::StopRendering()
 {
-	if ( emergency_state )
+	if ( !queue_thread || emergency_state )
 		return;
 	TextBufferCmd cmd;
 	cmd.type = TEXTBUFCMD_PAUSE;
@@ -349,7 +358,7 @@ void LFBTextBuffer::StopRendering()
 
 void LFBTextBuffer::ResumeRendering()
 {
-	if ( emergency_state )
+	if ( !queue_thread || emergency_state )
 		return;
 	ScopedLock lock(&queue_lock);
 	queue_is_paused = false;

kernel/lfbtextbuffer.h

@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2012, 2013, 2014.
+    Copyright(C) Jonas 'Sortie' Termansen 2012, 2013, 2014, 2015.
 
     This file is part of Sortix.
 
@@ -83,6 +83,7 @@ public:
 	virtual void SetCursorEnabled(bool enablecursor);
 	virtual TextPos GetCursorPos() const;
 	virtual void SetCursorPos(TextPos newcursorpos);
+	virtual void SpawnThreads();
 	virtual bool EmergencyIsImpaired();
 	virtual bool EmergencyRecoup();
 	virtual void EmergencyReset();

kernel/log.cpp

@@ -22,19 +22,31 @@
 
 *******************************************************************************/
 
+#include <assert.h>
 #include <stddef.h>
 #include <string.h>
 
+#include <sortix/kernel/addralloc.h>
 #include <sortix/kernel/kernel.h>
 #include <sortix/kernel/log.h>
+#include <sortix/kernel/pci.h>
+#include <sortix/kernel/pci-mmio.h>
 #include <sortix/kernel/textbuffer.h>
 
+#include "lfbtextbuffer.h"
+#include "multiboot.h"
 #include "textterminal.h"
 #include "vgatextbuffer.h"
 
 namespace Sortix {
 namespace Log {
 
+uint8_t* fallback_framebuffer = NULL;
+size_t fallback_framebuffer_bpp = 0;
+size_t fallback_framebuffer_pitch = 0;
+size_t fallback_framebuffer_width = 0;
+size_t fallback_framebuffer_height = 0;
+
 TextBufferHandle* device_textbufhandle = NULL;
 size_t (*device_callback)(void*, const char*, size_t) = NULL;
 size_t (*device_width)(void*) = NULL;
@@ -126,7 +138,34 @@ void Init(multiboot_info_t* bootinfo)
 
 	// Create the backend text buffer.
 	TextBuffer* textbuf;
-	if ( true )
+	if ( (bootinfo->flags & MULTIBOOT_INFO_FRAMEBUFFER_INFO) &&
+	     bootinfo->framebuffer_type != MULTIBOOT_FRAMEBUFFER_TYPE_EGA_TEXT )
+	{
+		assert(bootinfo->framebuffer_type == MULTIBOOT_FRAMEBUFFER_TYPE_RGB);
+		assert(bootinfo->framebuffer_bpp == 32);
+		assert(0 < bootinfo->framebuffer_width);
+		assert(0 < bootinfo->framebuffer_height);
+		pcibar_t fakebar;
+		fakebar.addr_raw = bootinfo->framebuffer_addr;
+		fakebar.size_raw = (uint64_t) bootinfo->framebuffer_pitch * bootinfo->framebuffer_height;
+		fakebar.addr_raw |= PCIBAR_TYPE_64BIT;
+		addralloc_t fb_alloc;
+		if ( !MapPCIBAR(&fb_alloc, fakebar, MAP_PCI_BAR_WRITE_COMBINE) )
+			Panic("Framebuffer setup failure.");
+		uint8_t* lfb = (uint8_t*) fb_alloc.from;
+		uint32_t lfbformat = bootinfo->framebuffer_bpp;
+		size_t scansize = bootinfo->framebuffer_pitch;
+		textbuf = CreateLFBTextBuffer(lfb, lfbformat, bootinfo->framebuffer_width,
+		                              bootinfo->framebuffer_height, scansize);
+		if ( !textbuf )
+			Panic(oom_msg);
+		fallback_framebuffer = lfb;
+		fallback_framebuffer_bpp = lfbformat;
+		fallback_framebuffer_width = bootinfo->framebuffer_width;
+		fallback_framebuffer_height = bootinfo->framebuffer_height;
+		fallback_framebuffer_pitch = bootinfo->framebuffer_pitch;
+	}
+	else
 	{
 		uint16_t* const VGAFB = (uint16_t*) 0xB8000;
 		const size_t VGA_WIDTH = 80;

kernel/scheduler.cpp

@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014.
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014, 2015.
 
     This file is part of Sortix.
 
@@ -378,6 +378,8 @@ Process* GetInitProcess()
 
 Process* GetKernelProcess()
 {
+	if ( !idle_thread )
+		return NULL;
 	return idle_thread->process;
 }
 

kernel/vga.cpp

@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2015.
 
     This file is part of Sortix.
 
@@ -39,8 +39,7 @@
 
 #include "fs/util.h"
 #include "vga.h"
-
-#define TEST_VGAFONT 0
+#include "vgafont.h"
 
 namespace Sortix {
 namespace VGA {
@@ -49,8 +48,6 @@ uint8_t* const VGA = (uint8_t* const) 0xB8000;
 const unsigned WIDTH = 80;
 const unsigned HEIGHT = 25;
 const size_t VGA_SIZE = sizeof(uint16_t) * WIDTH * HEIGHT;
-size_t vgafontsize;
-uint8_t* vgafont;
 
 static void WriteIndex(uint16_t port, uint8_t index, uint8_t value)
 {
@@ -103,26 +100,6 @@ static void FetchVGAFont(uint8_t* font)
 	WriteIndex(0x03CE, 0x04, old_03ce_04);
 }
 
-#if TEST_VGAFONT
-static void PrintFontChar(const uint8_t* font, unsigned char c)
-{
-	const uint8_t* glyph = font + VGA_FONT_CHARSIZE * (size_t) c;
-	for ( size_t y = 0; y < VGA_FONT_HEIGHT; y++ )
-	{
-		for ( size_t x = 0; x < VGA_FONT_WIDTH; x++ )
-		{
-			size_t bitindex = y * VGA_FONT_WIDTH + x;
-			uint8_t bitmap = glyph[bitindex/8UL];
-			uint8_t bitmod = bitindex % 8UL;
-			uint8_t bitmask = 1U << bitmod;
-			const char* toprint = (bitmap & bitmask) ? "X" : " ";
-			Log::Print(toprint);
-		}
-		Log::Print("\n");
-	}
-}
-#endif
-
 const uint8_t* GetFont()
 {
 	return vgafont;
@@ -130,26 +107,23 @@ const uint8_t* GetFont()
 
 void Init(const char* devpath, Ref<Descriptor> slashdev)
 {
-	vgafontsize = VGA_FONT_NUMCHARS * VGA_FONT_CHARSIZE;
-	if ( !(vgafont = new uint8_t[vgafontsize]) )
-		Panic("Unable to allocate vga font buffer");
-	FetchVGAFont(vgafont);
-#if TEST_VGAFONT
-	PrintFontChar(vgafont, 'A');
-	PrintFontChar(vgafont, 'S');
-#endif
+	if ( !Log::fallback_framebuffer )
+		FetchVGAFont(vgafont);
 
 	ioctx_t ctx; SetupKernelIOCtx(&ctx);
 
 	// Setup the vgafont device.
 	Ref<Inode> vgafontnode(new UtilMemoryBuffer(slashdev->dev, (ino_t) 0, 0, 0,
-	                                            0660, vgafont, vgafontsize,
+	                                            0660, vgafont, sizeof(vgafont),
 	                                            false, false));
 	if ( !vgafontnode )
 		PanicF("Unable to allocate %s/vgafont inode.", devpath);
 	if ( LinkInodeInDir(&ctx, slashdev, "vgafont", vgafontnode) != 0 )
 		PanicF("Unable to link %s/vgafont to vga font.", devpath);
 
+	if ( Log::fallback_framebuffer )
+		return;
+
 	// Setup the vga device.
 	Ref<Inode> vganode(new UtilMemoryBuffer(slashdev->dev, (ino_t) 0, 0, 0,
 	                                        0660, VGA, VGA_SIZE, true, false));

kernel/vgatextbuffer.cpp

@@ -192,6 +192,10 @@ void VGATextBuffer::UpdateCursor()
 		VGA::SetCursor(width, height-1);
 }
 
+void VGATextBuffer::SpawnThreads()
+{
+}
+
 bool VGATextBuffer::EmergencyIsImpaired()
 {
 	return false;

kernel/vgatextbuffer.h

@@ -48,6 +48,7 @@ public:
 	virtual void SetCursorEnabled(bool enablecursor);
 	virtual TextPos GetCursorPos() const;
 	virtual void SetCursorPos(TextPos cursorpos);
+	virtual void SpawnThreads();
 	virtual bool EmergencyIsImpaired();
 	virtual bool EmergencyRecoup();
 	virtual void EmergencyReset();

kernel/video.cpp

@@ -29,6 +29,7 @@
 #include <sortix/kernel/copy.h>
 #include <sortix/kernel/kernel.h>
 #include <sortix/kernel/kthread.h>
+#include <sortix/kernel/log.h>
 #include <sortix/kernel/string.h>
 #include <sortix/kernel/syscall.h>
 #include <sortix/kernel/textbuffer.h>
@@ -222,6 +223,20 @@ static int SetDriver(void* ptr, size_t size)
 	return 0;
 }
 
+static struct dispmsg_crtc_mode GetLogFallbackMode()
+{
+	struct dispmsg_crtc_mode mode;
+	memset(&mode, 0, sizeof(mode));
+	mode.control = DISPMSG_CONTROL_VALID;
+	mode.fb_format = Log::fallback_framebuffer_bpp;
+	mode.view_xres = (uint32_t) Log::fallback_framebuffer_width;
+	mode.view_yres = (uint32_t) Log::fallback_framebuffer_height;
+	mode.fb_location = 0;
+	mode.pitch = Log::fallback_framebuffer_width *
+	             Log::fallback_framebuffer_bpp / 8;
+	return mode;
+}
+
 static int SetCrtcMode(void* ptr, size_t size)
 {
 	struct dispmsg_set_crtc_mode msg;
@@ -232,18 +247,32 @@ static int SetCrtcMode(void* ptr, size_t size)
 
 	ScopedLock lock(&video_lock);
 
-	if ( num_devices <= msg.device )
+	if ( msg.device < num_devices )
+	{
+		DeviceEntry* device_entry = &devices[msg.device];
+		VideoDevice* device = device_entry->device;
+		if ( !device->SwitchMode(msg.connector, msg.mode) )
+			return -1;
+		// TODO: This could potentially fail.
+		if ( msg.device == ONE_AND_ONLY_DEVICE &&
+			 msg.connector == ONE_AND_ONLY_CONNECTOR )
+		{
+			Log::fallback_framebuffer = NULL;
+			Log::device_textbufhandle->Replace(device->CreateTextBuffer(msg.connector));
+		}
+	}
+	else if ( Log::fallback_framebuffer &&
+	          msg.device == ONE_AND_ONLY_DEVICE &&
+	          msg.connector == ONE_AND_ONLY_CONNECTOR )
+	{
+		struct dispmsg_crtc_mode fallback_mode = GetLogFallbackMode();
+		if ( memcmp(&msg.mode, &fallback_mode, sizeof(msg.mode)) != 0 )
+			return errno = EINVAL, -1;
+	}
+	else
+	{
 		return errno = ENODEV, -1;
-
-	DeviceEntry* device_entry = &devices[msg.device];
-	VideoDevice* device = device_entry->device;
-	if ( !device->SwitchMode(msg.connector, msg.mode) )
-		return -1;
-
-	// TODO: This could potentially fail.
-	if ( msg.device == ONE_AND_ONLY_DEVICE &&
-	     msg.connector == ONE_AND_ONLY_CONNECTOR )
-		Log::device_textbufhandle->Replace(device->CreateTextBuffer(msg.connector));
+	}
 
 	// No need to respond.
 
@@ -260,17 +289,27 @@ static int GetCrtcMode(void* ptr, size_t size)
 
 	ScopedLock lock(&video_lock);
 
-	if ( num_devices <= msg.device )
+	struct dispmsg_crtc_mode mode;
+	if ( Log::fallback_framebuffer &&
+	     msg.device == ONE_AND_ONLY_DEVICE &&
+	     msg.connector == ONE_AND_ONLY_CONNECTOR )
+	{
+		mode = GetLogFallbackMode();
+	}
+	else if ( msg.device < num_devices )
+	{
+		DeviceEntry* device_entry = &devices[msg.device];
+		VideoDevice* device = device_entry->device;
+		// TODO: There is no real way to detect failure here.
+		errno = 0;
+		mode = device->GetCurrentMode(msg.connector);
+		if ( !(mode.control & DISPMSG_CONTROL_VALID) && errno != 0 )
+			return -1;
+	}
+	else
+	{
 		return errno = ENODEV, -1;
-
-	DeviceEntry* device_entry = &devices[msg.device];
-	VideoDevice* device = device_entry->device;
-
-	// TODO: There is no real way to detect failure here.
-	errno = 0;
-	struct dispmsg_crtc_mode mode = device->GetCurrentMode(msg.connector);
-	if ( !(mode.control & DISPMSG_CONTROL_VALID) && errno != 0 )
-		return -1;
+	}
 
 	msg.mode = mode;
 
@@ -290,16 +329,28 @@ static int GetCrtcModes(void* ptr, size_t size)
 
 	ScopedLock lock(&video_lock);
 
-	if ( num_devices <= msg.device )
+	size_t nummodes = 0;
+	struct dispmsg_crtc_mode* modes = NULL;
+	if ( msg.device < num_devices )
+	{
+		DeviceEntry* device_entry = &devices[msg.device];
+		VideoDevice* device = device_entry->device;
+		modes = device->GetModes(msg.connector, &nummodes);
+		if ( !modes )
+			return -1;
+	}
+	else if ( Log::fallback_framebuffer &&
+	          msg.device == ONE_AND_ONLY_DEVICE &&
+	          msg.connector == ONE_AND_ONLY_CONNECTOR )
+	{
+		if ( !(modes = new struct dispmsg_crtc_mode[1]) )
+			return -1;
+		modes[nummodes++] = GetLogFallbackMode();
+	}
+	else
+	{
 		return errno = ENODEV, -1;
-
-	DeviceEntry* device_entry = &devices[msg.device];
-	VideoDevice* device = device_entry->device;
-
-	size_t nummodes;
-	struct dispmsg_crtc_mode* modes = device->GetModes(msg.connector, &nummodes);
-	if ( !modes )
-		return -1;
+	}
 
 	size_t requested_modes = msg.modes_length;
 	msg.modes_length = nummodes;
@@ -324,7 +375,6 @@ static int GetCrtcModes(void* ptr, size_t size)
 
 	delete[] modes;
 
-
 	return 0;
 }
 
@@ -338,8 +388,23 @@ static int GetMemorySize(void* ptr, size_t size)
 
 	ScopedLock lock(&video_lock);
 
-	if ( num_devices <= msg.device )
+	if ( Log::fallback_framebuffer &&
+	     msg.device == ONE_AND_ONLY_DEVICE )
+	{
+		msg.memory_size = Log::fallback_framebuffer_width *
+		                  Log::fallback_framebuffer_height *
+		                  Log::fallback_framebuffer_bpp / 8;
+	}
+	else if ( msg.device < num_devices )
+	{
+		DeviceEntry* device_entry = &devices[msg.device];
+		VideoDevice* device = device_entry->device;
+		msg.memory_size = device->FrameSize();
+	}
+	else
+	{
 		return errno = ENODEV, -1;
+	}
 
 	DeviceEntry* device_entry = &devices[msg.device];
 	VideoDevice* device = device_entry->device;
@@ -362,15 +427,60 @@ static int WriteMemory(void* ptr, size_t size)
 
 	ScopedLock lock(&video_lock);
 
-	if ( num_devices <= msg.device )
+	if ( Log::fallback_framebuffer &&
+	     msg.device == ONE_AND_ONLY_DEVICE )
+	{
+		size_t ideal_pitch = Log::fallback_framebuffer_width *
+		                     Log::fallback_framebuffer_bpp / 8;
+		if ( ideal_pitch == Log::fallback_framebuffer_pitch )
+		{
+			size_t framesize = Log::fallback_framebuffer_height *
+		                       Log::fallback_framebuffer_pitch;
+			if ( framesize < msg.offset )
+				return 0;
+			size_t count = msg.size;
+			size_t left = framesize - msg.offset;
+			if ( left < count )
+				count = left;
+			const uint8_t* src = msg.src;
+			uint8_t* dst = Log::fallback_framebuffer + msg.offset;
+			if ( !CopyFromUser(dst, src, count) )
+				return -1;
+		}
+		else
+		{
+			const uint8_t* src = msg.src;
+			size_t src_size = msg.size;
+			uint64_t y = msg.offset / ideal_pitch;
+			uint64_t x = msg.offset % ideal_pitch;
+			while ( src_size && y < Log::fallback_framebuffer_height )
+			{
+				size_t count = src_size;
+				if ( ideal_pitch -x < count )
+					count = ideal_pitch - x;
+				uint8_t* dst = Log::fallback_framebuffer +
+				               Log::fallback_framebuffer_pitch * y + x;
+				if ( !CopyFromUser(dst, src, count) )
+					return -1;
+				src += count;
+				src_size -= count;
+				x = 0;
+				y++;
+			}
+		}
+	}
+	else if ( msg.device < num_devices )
+	{
+		DeviceEntry* device_entry = &devices[msg.device];
+		VideoDevice* device = device_entry->device;
+		ioctx_t ctx; SetupUserIOCtx(&ctx);
+		if ( device->WriteAt(&ctx, msg.offset, msg.src, msg.size) < 0 )
+			return -1;
+	}
+	else
+	{
 		return errno = ENODEV, -1;
-
-	DeviceEntry* device_entry = &devices[msg.device];
-	VideoDevice* device = device_entry->device;
-
-	ioctx_t ctx; SetupUserIOCtx(&ctx);
-	if ( device->WriteAt(&ctx, msg.offset, msg.src, msg.size) < 0 )
-		return -1;
+	}
 
 	return 0;
 }
@@ -385,15 +495,60 @@ static int ReadMemory(void* ptr, size_t size)
 
 	ScopedLock lock(&video_lock);
 
-	if ( num_devices <= msg.device )
+	if ( Log::fallback_framebuffer &&
+	     msg.device == ONE_AND_ONLY_DEVICE )
+	{
+		size_t ideal_pitch = Log::fallback_framebuffer_width *
+		                     Log::fallback_framebuffer_bpp / 8;
+		if ( ideal_pitch == Log::fallback_framebuffer_pitch )
+		{
+			size_t framesize = Log::fallback_framebuffer_height *
+		                       Log::fallback_framebuffer_pitch;
+			if ( framesize < msg.offset )
+				return 0;
+			size_t count = msg.size;
+			size_t left = framesize - msg.offset;
+			if ( left < count )
+				count = left;
+			const uint8_t* src = Log::fallback_framebuffer + msg.offset;
+			uint8_t* dst = msg.dst;
+			if ( !CopyToUser(dst, src, count) )
+				return -1;
+		}
+		else
+		{
+			uint8_t* dst = msg.dst;
+			size_t dst_size = msg.size;
+			uint64_t y = msg.offset / ideal_pitch;
+			uint64_t x = msg.offset % ideal_pitch;
+			while ( dst_size && y < Log::fallback_framebuffer_height )
+			{
+				size_t count = dst_size;
+				if ( ideal_pitch -x < count )
+					count = ideal_pitch - x;
+				const uint8_t* src = Log::fallback_framebuffer +
+				                     Log::fallback_framebuffer_pitch * y + x;
+				if ( !CopyToUser(dst, src, count) )
+					return -1;
+				dst += count;
+				dst_size -= count;
+				x = 0;
+				y++;
+			}
+		}
+	}
+	else if ( msg.device < num_devices )
+	{
+		DeviceEntry* device_entry = &devices[msg.device];
+		VideoDevice* device = device_entry->device;
+		ioctx_t ctx; SetupUserIOCtx(&ctx);
+		if ( device->ReadAt(&ctx, msg.offset, msg.dst, msg.size) < 0 )
+			return -1;
+	}
+	else
+	{
 		return errno = ENODEV, -1;
-
-	DeviceEntry* device_entry = &devices[msg.device];
-	VideoDevice* device = device_entry->device;
-
-	ioctx_t ctx; SetupUserIOCtx(&ctx);
-	if ( device->ReadAt(&ctx, msg.offset, msg.dst, msg.size) < 0 )
-		return -1;
+	}
 
 	return 0;
 }

kernel/x64/boot.S

@@ -29,8 +29,13 @@
 	# Multiboot header.
 	.align 4
 	.long 0x1BADB002 # Magic.
-	.long 0x00000003 # Flags.
-	.long -(0x1BADB002 + 0x00000003) # Checksum
+	.long 0x00000007 # Flags.
+	.long -(0x1BADB002 + 0x00000007) # Checksum
+	.skip 32-12
+	.long 0 # Mode
+	.long 0 # Width
+	.long 0 # Height
+	.long 0 # Depth
 
 .section .bss, "aw", @nobits
 	.align 4096

kernel/x86/boot.S

@@ -29,8 +29,13 @@
 	# Multiboot header.
 	.align 4
 	.long 0x1BADB002 # Magic.
-	.long 0x00000003 # Flags.
-	.long -(0x1BADB002 + 0x00000003) # Checksum.
+	.long 0x00000007 # Flags.
+	.long -(0x1BADB002 + 0x00000007) # Checksum.
+	.skip 32-12
+	.long 0 # Mode
+	.long 0 # Width
+	.long 0 # Height
+	.long 0 # Depth
 
 .section .bss, "aw", @nobits
 	.align 4096