Re: [RFC PATCH 0/2] Expose available KVM free memory slot count to help avoid aborts

[Jan Kiszka <jan.kiszka@web.de>]

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On 2011-01-25 15:53, Avi Kivity wrote:
> On 01/25/2011 04:41 PM, Alex Williamson wrote:
>> >  >
>> >  >
>> >  >  kvm: Allow memory slot array to grow on demand
>> >  >
>> >  >  Remove fixed KVM_MEMORY_SLOTS limit, allowing the slot array
>> >  >  to grow on demand.  Private slots are now allocated at the
>> >  >  front instead of the end.  Only x86 seems to use private slots,
>> >
>> >  Hmm, doesn't current user space expect slots 8..11 to be the private
>> >  ones and wouldn't it cause troubles if slots 0..3 are suddenly
>> reserved?
>>
>> The private slots aren't currently visible to userspace, they're
>> actually slots 32..35.  The patch automatically increments user passed
>> slot ids so userspace has it's own zero-based view of the array.
>> Frankly, I don't understand why userspace reserves slots 8..11, is this
>> compatibility with older kernel implementations?
> 
> I think so.  I believe these kernel versions are too old now to matter,
> but of course I can't be sure.

Will check and enable those 4 additional slots for user space if we no
longer need to exclude them.

Jan


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