• Tomoki Sekiyama's avatar
    qemu-ga: Add Windows VSS provider and requester as DLL · b39297ae
    Tomoki Sekiyama authored
    
    
    Adds VSS provider and requester as a qga-vss.dll, which is loaded by
    Windows VSS service as well as by qemu-ga.
    
    "provider.cpp" implements a basic stub of a software VSS provider.
    Currently, this module only relays a frozen event from VSS service to the
    agent, and thaw event from the agent to VSS service, to block VSS process
    to keep the system frozen while snapshots are taken at the host.
    
    To register the provider to the guest system as COM+ application, the type
    library (.tlb) for qga-vss.dll is required. To build it from COM IDL (.idl),
    VisualC++, MIDL and stdole2.tlb in Windows SDK are required. This patch also
    adds pre-compiled .tlb file in the repository in order to enable
    cross-compile qemu-ga.exe for Windows with VSS support.
    
    "requester.cpp" provides the VSS requester to kick the VSS snapshot process.
    Qemu-ga.exe works without the DLL, although fsfreeze features are disabled.
    
    These functions are only supported in Windows 2003 or later. In older
    systems, fsfreeze features are disabled.
    
    In several versions of Windows which don't support attribute
    VSS_VOLSNAP_ATTR_NO_AUTORECOVERY, DoSnapshotSet fails with error
    VSS_E_OBJECT_NOT_FOUND. In this patch, we just ignore this error.
    To solve this fundamentally, we need a framework to handle mount writable
    snapshot on guests, which is required by VSS auto-recovery feature
    (cleanup phase after a snapshot is taken).
    Signed-off-by: default avatarTomoki Sekiyama <tomoki.sekiyama@hds.com>
    Signed-off-by: default avatarMichael Roth <mdroth@linux.vnet.ibm.com>
    b39297ae
configure 123 KB