physical memory allocator in DragonFly BSD

[Stéphanie Ouillon]

    Hello, 
        
        Venkatesh Srinivas made a comment on my gsoc application about
        implementing virtio drivers ( by the way, thank you about it ! I
        added some lines and time for the balloon driver ).
        I copy it :<span class="Apple-style-span"
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          "Just a warning -- the virtio balloon driver will likely
            involve a good amount of porting work; the NetBSD UVM is
            rather different than the DFly VM. The mechanism by which
            the balloon consumes "physical" memory will likely be
            different. On NetBSD, it probably uses something like
            uvm_pglistalloc()... I don't think we have a good contiguous
            physical memory allocator, so you might have to be careful."
        
      When NetBSD uses uvm_pglistalloc and
        uvm_pglistfree (I checked the code), DragonFly BSD will likely
        use contigmalloc and contigfree (like in FreeBSD) to deal with
        contiguous physical allocation.
        Well, I searched for some information, but could you explain me
        why I should be cautious with the physical memory allocation on
        DragonFly BSD, do you have encoutered any problem with it ? 
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        Thank you !
        
        Stéphanie