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NVME fails on big writes
NVME Compliance test 8:3.3.0 tries to write and read back big chunks of pages. Currently, on the latest QEMU operation of size 1024 blocks will fail when device is backed by a file.
NVME specification has several types of data transfers from guests, one of the is the PRP list (Physical Region Page List). PRP is a list of entries pointing to pages to be written. The list it self resides in a single or multiple pages.
NVME device maps the PRP list into QEMUSGList which will be me mapped into linux IO vectors. Finally, when the file driver will write the changes, it uses the posix pwritev, which fails if the number of vectors exceeds the maximum.
NVME Compliance - https://github.com/nvmecompliance/tnvme/wiki
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