[Bug 1777232] Re: NVME fails on big writes

[Thomas Huth]

The QEMU project is currently considering to move its bug tracking to another 
system. For this we need to know which bugs are still valid and which could be 
closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state 
back to "New" within the next 60 days, otherwise this report will be marked as 
"Expired". Or mark it as "Fix Released" if the problem has been solved with a 
newer version of QEMU already. Thank you and sorry for the inconvenience.

** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1777232

Title:
  NVME fails on big writes

Status in QEMU:
  Incomplete

Bug description:
  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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