On Fri, Jan 30, 2015 at 10:08:02PM +0100, Peter Lieven wrote: > Just wondering if VIRTQUEUE_MAX_SIZE in include/hw/virtio/virtio.h should not > be equal to IOV_MAX instead of the hardcoded 1024?
The vring queue size is guest-visible to some extent (e.g. vring memory layout). Tying it to a constant that is defined by the host operating system could lead to problems (e.g. live migration between different hosts). Anyway, all of the virtio devices have a queue size that is less than or equal to VIRTQUEUE_MAX_SIZE (and there is an assertion to check this in virtio_add_queue()). Guests are supposed to honor the vring queue size, although indirect descriptors seem to be able to use up to VIRTQUEUE_MAX_SIZE according to my understanding of QEMU's virtio.c code. Why would you like to use IOV_MAX? Stefan
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