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Written in C&inline assembly from scratch, ZeldaOS is an unix-like 32bit monolithic kernel which is designed to comform to POSIX.1 interface. At present, it's only able to run on any x86 and x86_64 processors. The name Zelda is from Nintendo video game: The Legend of Zelda

To build the project, we need a 64bit Linux host (I used a CentOS 7.3) and GCC suite(my GCC version is 4.8.5, other versioned gcc are supposed to work), in order to package a bootable ISO image, I also install rpm package:#yum install -y xorriso. the compilation tools will automatically generate 32bit elf objects withMakefile and Linker script

To build the image and ISO image(imagine the project top directory is/root/ZeldaOS/):

#ZELDA=/root/ZeldaOS/ make runtime_install#ZELDA=/root/ZeldaOS/ make app_install#ZELDA=/root/ZeldaOS/ make drive#ZELDA=/root/ZeldaOS/ make

To clean the built objects:

#ZELDA=/root/ZeldaOS/ make runtime_clean#ZELDA=/root/ZeldaOS/ make app_clean#ZELDA=/root/ZeldaOS/ make clean

There are two ways to launch the ZeldaOS:

this is the most usual way I did when I was debuging the code. you need to install qemu software beforehand, a typical command is given like:

#/usr/bin/qemu-system-x86_64 -serial tcp::4444,server -m 3024 -kernel Zelda.bin \-monitor null -nographic -vnc :100 -netdev tap,id=demonet0,ifname=demotap0,script=no,downscript=no \-device virtio-net-pci,netdev=demonet0,mac=52:53:54:55:56:00 \-netdev tap,id=demonet1,ifname=demotap1,script=no,downscript=no \-device virtio-net-pci,netdev=demonet1 -gdb tcp::5070

you can specify more different-serial parameter(qemu mannual) to observe the output or input. right here you can use the shell by telnet to local qemu serial endpoint:

#telnet localhost 4444....(omitted)Welcome to ZeldaOS Version 0.1Copyright (c) 2018 Jie Zheng [at] VMware[Link@Hyrule.kingdom /home/zelda]# unamesysname  : ZeldaOSnodename : Hyrulerelease  : The Braveversion  : 0.1machine  : i686domain   : kingdom[Link@Hyrule.kingdom /home/zelda]#[Link@Hyrule.kingdom /home/zelda]# ps    0 PL0:0x1060f6   kernel_idle_task          running                   /    1 PL3:0x40000c27 /usr/bin/userland_init    interruptible             /    2 PL0:0x104664   wq:ethernet_rx            interruptible             /    3 PL3:0x400013c8 /usr/bin/shelld           interruptible             /home/zelda    4 PL3:0x400013c8 /usr/bin/shelld           interruptible             /home/zelda    5 PL3:0x400013c8 /usr/bin/shelld           interruptible             /home/zelda    6 PL3:0x400013c8 /usr/bin/shelld           interruptible             /home/zelda    7 PL3:0x400013c8 /usr/bin/shelld           interruptible             /home/zelda    8 PL3:0x400013c8 /usr/bin/shelld           interruptible             /home/zelda    9 PL3:0x400013c8 /usr/bin/shelld           interruptible             /home/zelda   10 PL3:0x40000b24 ps                        running                   /home/zelda[Link@Hyrule.kingdom /dev]# ls -la ./ ./net./:FILE_TYPE_MARK        0        .FILE_TYPE_REGULAR     0        serial0FILE_TYPE_REGULAR     2000     ptm0FILE_TYPE_REGULAR     2000     ptm1FILE_TYPE_REGULAR     2000     ptm2FILE_TYPE_REGULAR     2000     ptm3FILE_TYPE_REGULAR     2000     ptm4FILE_TYPE_REGULAR     2000     ptm5FILE_TYPE_REGULAR     0        consoleFILE_TYPE_DIR         0        net./net:FILE_TYPE_MARK        0        .FILE_TYPE_REGULAR     0        Ethernet:0:3.0FILE_TYPE_REGULAR     0        Ethernet:0:4.0[Link@Hyrule.kingdom /usr/var]# tinyvm primes.vm23571113171923293137414347[Link@Hyrule.kingdom /home/zelda]# dummy0: Hello World1: Hello World^X[keyboard interrupted][Link@Hyrule.kingdom /home/zelda]#

In this case the kernel is booted by GRUB multiboot. you can burn theZelda.iso into a udisk drive or hard drive from which you can boot the kernel.we have the splash window when the kernel boots(grub draws it):

When the kernel is fully ready, thedefault console (which you can navigate to byAlt+F1) is displayed, there are other 6 consoles initiated by/usr/bin/userland_init, you can switch the console byAlt+F2 ... Alt+F7, you will observe console as below:

• x86
• PIC, APIC will be supported inZeldaOS.x86_64.
• interrupt management.
• x86_64 64bit support.
• Symmetric multiprocessing (SMP).
• SSE/AVX context save and restore
• hypervisor to lauch a VM with Intel VT-x(VMX)

• physical memory management.
• 4K paging(No 3G barrier break) for both kernel and PL3 tasks.
• Virtual Memory Area(VMA) management(per-task VMAs and kernel VMAs).
• paging fault handling, including page non-presence and page permission fault.
• kernel memory allocator.

• multitasking (PL0 tasks and PL3 tasks).
• task signal framework.
• Elf32 executable loading.
• task exception detection(e.g. illegal instruction, #GP, paging permission violation).
• Wait queue.
• Timer.
• bottom half schedule.
• kernel panic.

• Virtual File System (VFS).
• zeldafs as initramfs in Linux.
• memfs as tmpfs in Linux.
• devfs to expose kernel runtime data to userland.

• net packets management.
• Ethernet device interface.
• L2 multi-bridging(VLAN+MAC learning).
• L3 multi-routing(ARP, ICMP).
• overlay support(vxlan).
• userland networking extension(LWIP).

• Legacy virtio-net ethernet device driver(with revisionid == 0).
• vmxnet3 ethernet device support.
• PS/2 keyboard management.
• Programmable Interval Timer(PIT) management.
• serial port input/output management andserial console.
• ATA/IDE drive management.
• Lower level Text mode video buffer management.
• pseudo terminal console management.

• ZeldaOSruntime.
• newlib libc and libm port
• dynamic programming language support
• language-level VM support: portTinyvm without modifying even one line of code.
• system call list
• signal list
• multipleApplications running at Privilege Level 3