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@hannesm hannesm released this Apr 20, 2021


  • Allow mirage-crypto-rng-mirage 0.10 (@hannesm)
Assets 3

@dinosaure dinosaure released this Apr 19, 2021


Assets 3

@hannesm hannesm released this Mar 30, 2021


  • Adapt to conduit 2.3 and cohttp 4.0 (@samoht @dinosaure #1209)
  • Allow mirage-crypto-rng-mirage 0.9 (@hannesm #1218)
  • Adapt to tcpip 6.1.0 release (the unix sublibrary is no longer needed)
Assets 3

@hannesm hannesm released this Dec 4, 2020


  • Fix serialising of Mirage_key.Arg.ip_address: remove superfluous '.'
    character (#1205 @hannesm)
Assets 3

@hannesm hannesm released this Dec 2, 2020


IPv6 and dual (IPv4 and IPv6) stack support #1187

Since a long time, IPv6 code was around in our TCP/IP stack (thanks to @nojb
who developed it in 2014). Some months ago, @hannesm and @MagnusS got excited
to use it. After we managed to fix some bugs and add some test cases, and
writing more code to setup IPv6-only and dual stacks, we are eager to share
this support for MirageOS in a released version. We expect there to be bugs
lingering around, but duplicate address detection (neighbour solicitation and
advertisements) has been implemented, and (unless
"--accept-router-advertisement=false") router advertisements are decoded and
used to configure the IPv6 part of the stack. Configuring a static IPv6 address
is also possible (with "--ipv6=2001::42/64").

While at it, we unified the boot arguments between the different targets:
namely, on Unix (when using the socket stack), you can now pass
"--ipv4=" to the same effect as the direct stack: only listen
on (the subnet mask is ignored for the Unix socket stack).

A dual stack unikernel has "--ipv4-only=BOOL" and "--ipv6-only=BOOL" parameters,
so a unikernel binary could support both Internet Protocol versions, while the
operator can decide which protocol version to use.

Please also note that the default IPv4 network configuration no longer uses as default gateway (since there was no way to unset the default
gateway #1147).

For unikernel developers, there are some API changes in the Mirage module

  • New "v4v6" types for IP protocols and stacks
  • The ipv6_config record was adjusted in the same fashion as the ipv4_config
    type: it is now a record of a network (V6.Prefix.t) and gateway (V6.t option)

Some parts of the Mirage_key module were unified as well:

  • Arp.ip_address is available (for a dual Ipaddr.t)
  • Arg.ipv6_address replaces Arg.ipv6 (for an Ipaddr.V6.t)
  • Arg.ipv6 replaces Arg.ipv6_prefix (for a Ipaddr.V6.Prefix.t)
  • and V6.gateway are available, mirroring the V4 submodule

If you're ready to experiment with the dual stack, here's a diff for our basic
network example (from mirage-skeleton/device-usage/network) replacing IPv4
with a dual stack:

diff --git a/device-usage/network/ b/device-usage/network/
Assets 3

@hannesm hannesm released this Oct 24, 2020


The Xen backend is a minimal legacy-free re-write: Solo5 (since 0.6.6) provides
the low-level glue code, and ocaml-freestanding provides the OCaml runtime. The
PV-only Mini-OS implementation has been retired.

The only supported virtualization mode is now Xen PVH (version 2 or above),
supported since Xen version 4.10 or later (and Qubes OS 4.0).

The support for the ARM32 architecture on Xen has been removed.

Security posture improvements:

With the move to a Solo5 and ocaml-freestanding base MirageOS gains several
notable improvements to security posture for unikernels on Xen:

  • Stack smashing protection is enabled unconditionally for all C code.
  • W^X is enforced throughout, i.e. .text is read-execute, .rodata is
    read-only, non-executable and .data, heap and stack are read-write and
  • The memory allocator used by the OCaml runtime is now dlmalloc (provided by
    ocaml-freestanding), which is a big improvement over the Mini-OS malloc, and
    incorporates features such as heap canaries.

Interface changes:

  • With the rewrite of the Xen core platform stack, several Xen-specific APIs
    have changed in incompatible ways; unikernels may need to be updated. Please
    refer to the mirage-xen v6.0.0 change
    for a list of
    interfaces that have changed along with their replacements.

Other changes:

  • OCaml 4.08 is the minimum supported version.
  • A dummy dev-repo field is emitted for the generated opam file.
  • .xe files are no longer generated.
  • Previous versions of MirageOS would strip boot parameters on Xen, since Qubes
    OS 3.x added arguments that could not be interpreted by our command line
    parser. Since Qubes OS 4.0 this is no longer an issue, and MirageOS no longer
    strips any boot parameters. You may need to execute
    qvm-prefs qube-name kernelopts ''.


  • Thanks to Roger Pau Monné, Andrew Cooper and other core Xen developers for
    help with understanding the specifics of how PVHv2 works, and how to write an
    implementation from scratch.
  • Thanks to Marek Marczykowski-Górecki for help with the Qubes OS specifics, and
    for forward-porting some missing parts of PVHv2 to Qubes OS version of Xen.
  • Thanks to @palainp on Github for help with testing on Qubes OS.
Assets 3

@hannesm hannesm released this Sep 22, 2020


  • OCaml runtime parameters (OCAMLPARAM) are exposed as boot and configure
    arguments. This allows e.g. to switch to the best-fit garbage collection
    strategy (#1180 @hannesm)
Assets 3

@hannesm hannesm released this Jun 22, 2020


  • Emit type=pv in xl (instead of builder=linux), as required by xen 4.10+ (#1166 by @djs55)
  • adapt to ipaddr 5.0.0, tcpip 5.0.0, mirage-crypto 0.8 (#1172 @hannesm)
Assets 3

@hannesm hannesm released this May 18, 2020


  • handle errors from Bos.OS.Cmd.run_out
  • use PREFIX if defined (no need to call "opam config var prefix")
  • adapt to conduit 2.2.0, tls 0.12, mirage-crypto 0.7.0 changes
Assets 3

@hannesm hannesm released this Mar 18, 2020


Assets 3