On Mon, Oct 04, 2021 at 09:38:00PM +0200, Christian Schoenebeck wrote: > At the moment the maximum transfer size with virtio is limited to 4M > (1024 * PAGE_SIZE). This series raises this limit to its maximum > theoretical possible transfer size of 128M (32k pages) according to the > virtio specs: > > https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-240006
Hi Christian, I took a quick look at the code: - The Linux 9p driver restricts descriptor chains to 128 elements (net/9p/trans_virtio.c:VIRTQUEUE_NUM) - The QEMU 9pfs code passes iovecs directly to preadv(2) and will fail with EINVAL when called with more than IOV_MAX iovecs (hw/9pfs/9p.c:v9fs_read()) Unless I misunderstood the code, neither side can take advantage of the new 32k descriptor chain limit? Thanks, Stefan
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