[Qemu-devel] [Bug 1474263] [NEW] "Image format was not specified" warning should be suppressed for the vvfat (and probably nbd) driver

[felix]

Public bug reported:

Running

qemu -drive file.driver=vvfat,file.dir=.

displays

WARNING: Image format was not specified for 'json:{"dir": ".", "driver": 
"vvfat"}' and probing guessed raw.
         Automatically detecting the format is dangerous for raw images, write 
operations on block 0 will be restricted.
         Specify the 'raw' format explicitly to remove the restrictions.

However, since "images" provided by the vvfat driver are always raw (and
the first sector isn't writeable in any case), this warning is
superfluous and should not be displayed.

A similar warning is displayed for NBD devices; I suspect it should be
also disabled for similar reasons, but I'm not sure if serving non-raw
images is actually a violation of the protocol. qemu-nbd translates them
to raw images, for what it's worth, even if it may be suppressed with -f
raw.

Noticed on 2.3.0; the code that causes this behaviour is still
apparently present in today's git master
(f3a1b5068cea303a55e2a21a97e66d057eaae638). Speaking of versions: you
may want to update the copyright notice that qemu -version displays.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1474263

Title:
  "Image format was not specified" warning should be suppressed for the
  vvfat (and probably nbd) driver

Status in QEMU:
  New

Bug description:
  Running

  qemu -drive file.driver=vvfat,file.dir=.

  displays

  WARNING: Image format was not specified for 'json:{"dir": ".", "driver": 
"vvfat"}' and probing guessed raw.
           Automatically detecting the format is dangerous for raw images, 
write operations on block 0 will be restricted.
           Specify the 'raw' format explicitly to remove the restrictions.

  However, since "images" provided by the vvfat driver are always raw
  (and the first sector isn't writeable in any case), this warning is
  superfluous and should not be displayed.

  A similar warning is displayed for NBD devices; I suspect it should be
  also disabled for similar reasons, but I'm not sure if serving non-raw
  images is actually a violation of the protocol. qemu-nbd translates
  them to raw images, for what it's worth, even if it may be suppressed
  with -f raw.

  Noticed on 2.3.0; the code that causes this behaviour is still
  apparently present in today's git master
  (f3a1b5068cea303a55e2a21a97e66d057eaae638). Speaking of versions: you
  may want to update the copyright notice that qemu -version displays.

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