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OSv, a new operating system for the cloud.
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wkozaczuk Changed loader to print total boot time by default
Signed-off-by: Waldemar Kozaczuk <>
Latest commit c839511 Mar 25, 2019
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apps @ 333b84a Updated apps Mar 12, 2019
conf build: move arch-specific configuration to conf/$(arch).mk Jun 18, 2014
core Changed loader to print total boot time by default Mar 26, 2019
documentation fix permissions on LICENSE-prex Feb 6, 2018
external nfs: Add a makefile option to build in libnfs. Dec 20, 2015
images Remove deprecated "mgmt" submodule Jul 26, 2016
include Changed loader to print total boot time by default Mar 26, 2019
libc Add libc aliases to some mathematical functions Nov 28, 2018
modules Adjusted REST api server to print it listen on port Mar 10, 2019
musl @ 372a948 Add musl git submodule Aug 4, 2014
scripts Refactor and enhance firecracker script Mar 25, 2019
tests Reset FPU state after saving it and upon context switch Jan 29, 2019
.gitignore Added some extra files to .gitignore Jul 7, 2018
.gitmodules Split httpserver module into httpserver-api and httpserver-html5-gui Sep 10, 2017 Add line breaks to CODINGSTYLE Jan 26, 2015
Doxyfile doxygen: add include strip path Sep 16, 2014
PORTING README: document -j option on make / scripts/build Nov 19, 2018
bootfs.manifest.skel Add vdso fast syscall compatibility library Mar 18, 2018
bootfs_empty.manifest.skel Changed build script to use empty bootfs for ROFS images Jul 29, 2018
config.json Remove deprecated "mgmt" submodule Jul 26, 2016 loader: add a dummy shared library to the build Dec 23, 2012 Add missing readlinkat function and corresponding syscall Feb 25, 2019 Changed loader to print total boot time by default Mar 26, 2019 Stub implementation of mkfifoat() Aug 14, 2018
usr_rofs.manifest.skel Implemented Read-Only File System (ROFS) Mar 22, 2018


OSv is a new open-source operating system for virtual-machines. OSv was designed from the ground up to execute a single application on top of a hypervisor, resulting in superior performance and effortless management when compared to traditional operating systems which were designed for a vast range of physical machines.

OSv has new APIs for new applications, but also runs unmodified Linux applications (most of Linux's ABI is supported) and in particular can run an unmodified JVM, and applications built on top of one.

For more information about OSv, see and



OSv can only be built on a 64-bit x86 Linux distribution. Please note that this means the "x86_64" or "amd64" version, not the 32-bit "i386" version.

If you wish, you can run the script 'scripts/' as root to install all dependencies. Otherwise, you may follow the manual instructions below.

First, install prerequisite packages:



Debian stable(wheezy) Debian stable(wheezy) requires to compile gcc, gdb and qemu. And also need to configure bridge manually.

More details are available on wiki page: Building OSv on Debian stable

Debian testing(jessie)

apt-get install build-essential libboost-all-dev genromfs autoconf libtool openjdk-7-jdk ant qemu-utils maven libmaven-shade-plugin-java python-dpkt tcpdump gdb qemu-system-x86 gawk gnutls-bin openssl python-requests lib32stdc++-4.9-dev p11-kit

Arch Linux

pacman -S base-devel git python apache-ant maven qemu gdb boost yaml-cpp unzip openssl-1.0

Apply the following patch to make it work with openssl-1.0

diff --git a/modules/lua/Makefile b/modules/lua/Makefile
index 9676f349..ddb6a075 100644
--- a/modules/lua/Makefile
+++ b/modules/lua/Makefile
@@ -123,7 +123,7 @@ $(CDIR)/ssl.lua: $(LUA_ROCKS_BIN)
 # Workaround because LuaRocks ignores /lib64
 ifneq ("$(wildcard /usr/lib64/*)", "")
-       out/bin/luarocks install LuaSec 0.5 OPENSSL_LIBDIR=/usr/lib64
+       out/bin/luarocks install LuaSec 0.5 OPENSSL_LIBDIR=/usr/lib/openssl-1.0 OPENSSL_INCDIR=/usr/include/openssl-1.0
        out/bin/luarocks install LuaSec 0.5

Before start building OSv, you'll need to add your account to kvm group.

usermod -aG kvm <user name>



You may use Oracle JDK if you don't want to pull too many dependencies for openjdk-7-jdk

To ensure functional C++11 support, Gcc 4.8 or above is required, as this was the first version to fully comply with the C++11 standard.

Make sure all git submodules are up-to-date:

git submodule update --init --recursive

Finally, build everything at once:

make -j$(nproc)

to build only the OSv kernel, or more usefully,

scripts/build -j$(nproc)

to build an image of the OSv kernel and the default application.

Command nproc (embedded in bash/core-utils) will calculte the number of jobs/threads for make and scripts/build automatically. Alternatively, the environment variable MAKEFLAGS can be exported as follows:

export MAKEFLAGS=-j$(nproc)

In that case, make and scripts/build do not need the parameter -j.

scripts/build creates the image build/last/usr.img in qcow2 format. To convert this image to other formats, use the scripts/convert tool, which can create an image in the vmdk, vdi, raw, or qcow2-old formats (qcow2-old is an older qcow2 format, compatible with older versions of QEMU). For example:

scripts/convert raw

By default make will use the static libraries and headers of gcc in external submodule. To change this pass host via *_env variables:

make build_env=host

This will use static libraries and headers in the system instead (make sure they are installed before run make), if you only want to use C++ static libraries in the system, just set cxx_lib_env to host:

make cxx_lib_env=host

Running OSv


By default, this runs OSv under KVM, with 4 VCPUs and 2GB of memory, and runs the default management application containing a shell, a REST API server and a browser base dashboard (at port 8000).

If running under KVM you can terminate by hitting Ctrl+A X.

External Networking

To start osv with external networking:

sudo ./scripts/ -n -v

The -v is for kvm's vhost that provides better performance and its setup requires a tap and thus we use sudo.

By default OSv spawns a dhcpd that auto config the virtual nics. Static config can be done within OSv, configure networking like so:

ifconfig virtio-net0 netmask up
route add default gw

Test networking:

test invoke TCPExternalCommunication

Running Java or C applications that already reside within the image:

# Building and running a simple java application example
$ scripts/build image=java-example
$ scripts/ -e " -cp /java-example Hello"

# Running an ifconfig by explicit execution of (compiled C++ code)
$ scripts/build
$ sudo scripts/ -nv -e "/tools/"
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