Re: [PATCH 0/2] virtio-pci: fix abort when fail to allocate ioeventfd

[Avi Kivity <avi@redhat.com>]

On 03/13/2012 12:42 PM, Amos Kong wrote:
> Boot up guest with 232 virtio-blk disk, qemu will abort for fail to
> allocate ioeventfd. This patchset changes kvm_has_many_ioeventfds(),
> and check if available ioeventfd exists. If not, virtio-pci will
> fallback to userspace, and don't use ioeventfd for io notification.

How about an alternative way of solving this, within the memory core:
trap those writes in qemu and write to the ioeventfd yourself.  This way
ioeventfds work even without kvm:


  core: create eventfd
  core: install handler for memory address that writes to ioeventfd
  kvm (optional): install kernel handler for ioeventfd

even if the third step fails, the ioeventfd still works, it's just slower.

-- 
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