[Xen-devel] How to deallocate memory shared between domain and xen

["Santos, Jose Renato G" <joserenato.santos@xxxxxx>]

  Hi,

  Can someone more experienced with memory management in Xen give me
  some advice?
  I am not sure how should I free memory shared between Xen and a
domain.
  This is part of my effort to port xenoprof to SMP guests.

  I used the code in trace.c as an example of how to allocate
  pages shared between Xen and a domain. This is how the
  shared pages are allocated:
  a) In Xen:
      - allocate pages from Xen heap using "alloc_xenheap_pages(order)"
      - share each page with domain using "SHARE_PFN_WITH_DOMAIN(page,
domain)"
  b) In kernel
      - reserve contiguous kernel virtual area using "get_vm_area(size,
VM_IOREMAP)"
      - Map shared pages into kernel virtual area using
"direct_remap_area_pages()"

  This seems to be working fine.
  Now, I am not sure what is the sequence of operations to deallocate
these
  shared pages when they are not needed anymore. I spent sometime 
  looking at the code but I still don't have a clear understanding
  of how memory is managed in Xen. 

  Any help is greatly appreciated, as will save me a lot of time ...


  Thanks

  Renato


     

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