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d400b8fb18
Commit 1b1402b introduced a regression. Since older libvirt versions would silently round memory up (until the previous patch), but populated current memory based on querying the guest, it was possible to have dumpxml show cur > max by the amount of the rounding. For example, if a user requested 1048570 KiB memory (just shy of 1GiB), the qemu driver would actually run with 1048576 KiB, and libvirt 0.9.10 would output a current that was 6KiB larger than the maximum. Situations where this could have an impact include, but are not limited to, migration from old to new libvirt, managedsave in old libvirt and start in new libvirt, snapshot creation in old libvirt and revert in new libvirt - without this patch, the new libvirt would reject the VM because of the rounding discrepancy. Fix things by adding a fuzz factor, and silently clamp current down to maximum in that case, rather than failing to reparse XML for an existing VM. From a practical standpoint, this has no user impact: 'virsh dumpxml' will continue to query the running guest rather than rely on the incoming xml, which will see the currect current value, and even if clamping down occurs during parsing, it will be by at most the fuzz factor of a megabyte alignment, and rounded back up when passed back to the hypervisor. Meanwhile, we continue to reject cur > max if the difference is beyond the fuzz factor of nearest megabyte. But this is not a real change in behavior, since with 0.9.10, even though the parser allowed it, later in the processing stream we would reject it at the qemu layer; so rejecting it in the parser just moves error detection to a nicer place. * src/conf/domain_conf.c (virDomainDefParseXML): Don't reject existing XML. Based on a report by Zhou Peng.
libvirt library code README
===========================
The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.
The files directly in this directory are supporting the public API
entry points & data structures.
There are two core shared modules to be aware of:
* util/ - a collection of shared APIs that can be used by any
code. This directory is always in the include path
for all things built
* conf/ - APIs for parsing / manipulating all the official XML
files used by the public API. This directory is only
in the include path for driver implementation modules
* vmx/ - VMware VMX config handling (used by esx/ and vmware/)
Then there are the hypervisor implementations:
* esx/ - VMware ESX and GSX support using vSphere API over SOAP
* hyperv/ - Microsoft Hyper-V support using WinRM
* lxc/ - Linux Native Containers
* openvz/ - OpenVZ containers using cli tools
* phyp/ - IBM Power Hypervisor using CLI tools over SSH
* qemu/ - QEMU / KVM using qemu CLI/monitor
* remote/ - Generic libvirt native RPC client
* test/ - A "mock" driver for testing
* uml/ - User Mode Linux
* vbox/ - Virtual Box using native API
* vmware/ - VMware Workstation and Player using the vmrun tool
* xen/ - Xen using hypercalls, XenD SEXPR & XenStore
* xenapi/ - Xen using libxenserver
Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU, UML and Xen drivers.
The ESX, Hyper-V, Power Hypervisor, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly
* cpu/ - CPU feature management
* interface/ - Host network interface management
* network/ - Virtual NAT networking
* nwfilter/ - Network traffic filtering rules
* node_device/ - Host device enumeration
* secret/ - Secret management
* security/ - Mandatory access control drivers
* storage/ - Storage management drivers
Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories