Event Log Buffers

Event log buffers are composed of from 1 to 512 pages of memory, which makes the event log buffers from 4 KB to 2 MB in size. A partition calls the HvCreateEventLogBuffer hypercall function to individually create buffers, and the size and limit of each buffer are determined from the event log buffer group's geometry. For more information about the geometry of event log buffer groups, see Event Log Buffer Groups. The hypervisor allocates the pages that constitute each buffer from the partition's pool.

When the hypervisor creates a buffer, the hypervisor allocates and initializes pages for the buffer. However, the buffer remains inaccessible to the guest. Therefore, the partition must call the HvMapEventLogBuffer hypercall function to map the buffer into the guest's address space prior to access. Mapping the buffer creates read-only overlay pages in the guest's address space and returns the guest physical addresses (GPAs) of the pages that constitute the buffer. The buffer remains read-only accessible until the partition calls the HvUnmapEventLogBuffer hypercall function to unmap the buffer. When the partition calls the HvDeleteEventLogBuffer hypercall function, the hypervisor returns the buffer's pages to the partition's pool that they were allocated from.

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Build date: 11/16/2013