BuildSystem: Rework calling qemu

I change always manually the serial/graphical. When running cmake
you can define variable QEMU_ACCEL that will be used as accelerator.

Also ninja has the following targets for running qemu
  1. qemu:            Run graphical qemu environment
  2. qemu-nographic:  Run qemu without graphical screen. You should
                      select 'serial only' from grub menu.
  3. qemu-debug:      Run qemu without accelerator and interrupt
                      debugger.

CMakeLists.txt

@@ -20,6 +20,10 @@ if(NOT EXISTS ${CMAKE_CXX_COMPILER})
 	set(CMAKE_CXX_COMPILER g++)
 endif()
 
+if(DEFINED QEMU_ACCEL)
+	set(QEMU_ACCEL -accel ${QEMU_ACCEL})
+endif()
+
 add_compile_options(-mno-sse -mno-sse2)
 add_compile_definitions(__enable_sse=0)
 
@@ -90,13 +94,19 @@ add_custom_target(check-fs
 )
 
 add_custom_target(qemu
-	COMMAND ${CMAKE_COMMAND} -E env BANAN_ARCH="${BANAN_ARCH}" DISK_IMAGE_PATH="${DISK_IMAGE_PATH}" ${CMAKE_SOURCE_DIR}/qemu.sh -accel kvm
+	COMMAND ${CMAKE_COMMAND} -E env BANAN_ARCH="${BANAN_ARCH}" DISK_IMAGE_PATH="${DISK_IMAGE_PATH}" ${CMAKE_SOURCE_DIR}/qemu.sh -serial stdio ${QEMU_ACCEL}
+	DEPENDS image
+	USES_TERMINAL
+)
+
+add_custom_target(qemu-nographic
+	COMMAND ${CMAKE_COMMAND} -E env BANAN_ARCH="${BANAN_ARCH}" DISK_IMAGE_PATH="${DISK_IMAGE_PATH}" ${CMAKE_SOURCE_DIR}/qemu.sh -nographic ${QEMU_ACCEL}
 	DEPENDS image
 	USES_TERMINAL
 )
 
 add_custom_target(qemu-debug
-	COMMAND ${CMAKE_COMMAND} -E env BANAN_ARCH="${BANAN_ARCH}" DISK_IMAGE_PATH="${DISK_IMAGE_PATH}" ${CMAKE_SOURCE_DIR}/qemu.sh -d int -no-reboot
+	COMMAND ${CMAKE_COMMAND} -E env BANAN_ARCH="${BANAN_ARCH}" DISK_IMAGE_PATH="${DISK_IMAGE_PATH}" ${CMAKE_SOURCE_DIR}/qemu.sh -serial stdio -d int -no-reboot
 	DEPENDS image
 	USES_TERMINAL
 )

PreLoad.cmake

@@ -0,0 +1 @@
+set(CMAKE_GENERATOR "Ninja" CACHE INTERNAL "" FORCE)

README.md

@@ -14,18 +14,20 @@ Each major component and library has its own subdirectory (kernel, userspace, li
 
 There does not exist a complete list of needed packages for building. From the top of my head I can say that *cmake*, *ninja*, *make*, *grub*, *rsync* and emulator (*qemu* or *bochs*) are needed.
 
+You can and *should* pass cmake variable QEMU_ACCEL set to proper accelerator to cmake commands. For example on Linux this means adding -DQEMU_ACCEL=kvm to the end of all cmake commands. 
+
 Create the build directory and cofigure cmake
 ```sh
 mkdir build
 cd build
-cmake -G Ninja ..
+cmake ..
 ```
 
 To build the toolchain for this os. You can run the following command.
 > ***NOTE:*** The following step has to be done only once. This might take a long time since we are compiling binutils and gcc.
 ```sh
 ninja toolchain
-cmake -G Ninja --fresh .. # We need to reconfigure cmake to use the new compiler
+cmake --fresh .. # We need to reconfigure cmake to use the new compiler
 ninja libstdc++
 ```
 

qemu.sh

@@ -5,5 +5,4 @@ qemu-system-$BANAN_ARCH										\
 	-m 128													\
 	-smp 2													\
 	-drive format=raw,media=disk,file=${DISK_IMAGE_PATH}	\
-	-serial stdio											\
 	$@														\