50de920b37
Introduce the following fw_cfg files: - "etc/smi/supported-features": a little endian uint64_t feature bitmap, presenting the features known by the host to the guest. Read-only for the guest. The content of this file will be determined via bit-granularity ICH9-LPC device properties, to be introduced later. For now, the bitmask is left zeroed. The bits will be set from machine type compat properties and on the QEMU command line, hence this file is not migrated. - "etc/smi/requested-features": a little endian uint64_t feature bitmap, representing the features the guest would like to request. Read-write for the guest. The guest can freely (re)write this file, it has no direct consequence. Initial value is zero. A nonzero value causes the SMI-related fw_cfg files and fields that are under guest influence to be migrated. - "etc/smi/features-ok": contains a uint8_t value, and it is read-only for the guest. When the guest selects the associated fw_cfg key, the guest features are validated against the host features. In case of error, the negotiation doesn't proceed, and the "features-ok" file remains zero. In case of success, the "features-ok" file becomes (uint8_t)1, and the negotiated features are locked down internally (to which no further changes are possible until reset). The initial value is zero. A nonzero value causes the SMI-related fw_cfg files and fields that are under guest influence to be migrated. The C-language fields backing the "supported-features" and "requested-features" files are uint8_t arrays. This is because they carry guest-side representation (our choice is little endian), while VMSTATE_UINT64() assumes / implies host-side endianness for any uint64_t fields. If we migrate a guest between hosts with different endiannesses (which is possible with TCG), then the host-side value is preserved, and the host-side representation is translated. This would be visible to the guest through fw_cfg, unless we used plain byte arrays. So we do. Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Igor Mammedov <imammedo@redhat.com> Message-Id: <20170126014416.11211-2-lersek@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
QEMU README
===========
QEMU is a generic and open source machine & userspace emulator and
virtualizer.
QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).
QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.
QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.
QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.
Building
========
QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:
mkdir build
cd build
../configure
make
Additional information can also be found online via the QEMU website:
http://qemu-project.org/Hosts/Linux
http://qemu-project.org/Hosts/Mac
http://qemu-project.org/Hosts/W32
Submitting patches
==================
The QEMU source code is maintained under the GIT version control system.
git clone git://git.qemu-project.org/qemu.git
When submitting patches, the preferred approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the HACKING and CODING_STYLE files.
Additional information on submitting patches can be found online via
the QEMU website
http://qemu-project.org/Contribute/SubmitAPatch
http://qemu-project.org/Contribute/TrivialPatches
Bug reporting
=============
The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:
https://bugs.launchpad.net/qemu/
If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.
For additional information on bug reporting consult:
http://qemu-project.org/Contribute/ReportABug
Contact
=======
The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC
- qemu-devel@nongnu.org
http://lists.nongnu.org/mailman/listinfo/qemu-devel
- #qemu on irc.oftc.net
Information on additional methods of contacting the community can be
found online via the QEMU website:
http://qemu-project.org/Contribute/StartHere
-- End