In racing situations between hotplug events and migration operation,
a rtas hotplug event could have not yet be delivered to the source
guest when migration is started. In this case the pending_events of
spapr state need be transmitted to the target so that the hotplug
event can be finished on the target.
To achieve the minimal VMSD possible to migrate the pending_events list,
this patch makes the changes in spapr_events.c:
- 'log_type' of sPAPREventLogEntry struct deleted. This information can be
derived by inspecting the rtas_error_log summary field. A new function
called 'spapr_event_log_entry_type' was added to retrieve the type of
a given sPAPREventLogEntry.
- sPAPREventLogEntry, epow_log_full and hp_log_full were redesigned. The
only data we're going to migrate in the VMSD is the event log data itself,
which can be divided in two parts: a rtas_error_log header and an extended
event log field. The rtas_error_log header contains information about the
size of the extended log field, which can be used inside VMSD as the size
parameter of the VBUFFER_ALOC field that will store it. To allow this use,
the header.extended_length field must be exposed inline to the VMSD instead
of embedded into a 'data' field that holds everything. With this in mind,
the following changes were done:
* a new 'header' field was added to sPAPREventLogEntry. This field holds a
a struct rtas_error_log inline.
* the declaration of the 'rtas_error_log' struct was moved to spapr.h
to be visible to the VMSD macros.
* 'data' field of sPAPREventLogEntry was renamed to 'extended_log' and
now holds only the contents of the extended event log.
* 'struct rtas_error_log hdr' were taken away from both epow_log_full
and hp_log_full. This information is now available at the header field of
sPAPREventLogEntry.
* epow_log_full and hp_log_full were renamed to epow_extended_log and
hp_extended_log respectively. This rename makes it clearer to understand
the new purpose of both structures: hold the information of an extended
event log field.
* spapr_powerdown_req and spapr_hotplug_req_event now creates a
sPAPREventLogEntry structure that contains the full rtas log entry.
* rtas_event_log_queue and rtas_event_log_dequeue now receives a
sPAPREventLogEntry pointer as a parameter instead of a void pointer.
- the endianess of the sPAPREventLogEntry header is now native instead
of be32. We can use the fields in native endianess internally and write
them in be32 in the guest physical memory inside 'check_exception'. This
allows the VMSD inside spapr.c to read the correct size of the
entended_log field.
- inside spapr.c, pending_events is put in a subsection in the spapr state
VMSD to make sure migration across different versions is not broken.
A small change in rtas_event_log_queue and rtas_event_log_dequeue were also
made: instead of calling qdev_get_machine(), both functions now receive
a pointer to the sPAPRMachineState. This pointer is already available in
the callers of these functions and we don't need to waste resources
calling qdev() again.
Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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