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Diffstat (limited to 'docs/devel/memory.rst')
| -rw-r--r-- | docs/devel/memory.rst | 17 |
1 files changed, 6 insertions, 11 deletions
diff --git a/docs/devel/memory.rst b/docs/devel/memory.rst index 42d3ca29c4..f22146e56c 100644 --- a/docs/devel/memory.rst +++ b/docs/devel/memory.rst @@ -165,17 +165,14 @@ and finalized one by one. The order in which memory regions will be finalized is not guaranteed. If however the memory region is part of a dynamically allocated data -structure, you should call object_unparent() to destroy the memory region -before the data structure is freed. For an example see VFIOMSIXInfo -and VFIOQuirk in hw/vfio/pci.c. +structure, you should free the memory region in the instance_finalize +callback. For an example see VFIOMSIXInfo and VFIOQuirk in +hw/vfio/pci.c. You must not destroy a memory region as long as it may be in use by a device or CPU. In order to do this, as a general rule do not create or -destroy memory regions dynamically during a device's lifetime, and only -call object_unparent() in the memory region owner's instance_finalize -callback. The dynamically allocated data structure that contains the -memory region then should obviously be freed in the instance_finalize -callback as well. +destroy memory regions dynamically during a device's lifetime, and never +call object_unparent(). If you break this rule, the following situation can happen: @@ -201,9 +198,7 @@ this exception is rarely necessary, and therefore it is discouraged, but nevertheless it is used in a few places. For regions that "have no owner" (NULL is passed at creation time), the -machine object is actually used as the owner. Since instance_finalize is -never called for the machine object, you must never call object_unparent -on regions that have no owner, unless they are aliases or containers. +machine object is actually used as the owner. Overlapping regions and priority |