Re: [PATCH] doc: do not recommend -blockdev

["Alex Bennée" <alex.bennee@linaro.org>]

Michael Tokarev <mjt@tls.msk.ru> writes:

> Currently, documentation recommends to use -blockdev instead of -drive.
> This is quite a bit misleading, because -blockdev is "too" low-level,
> requires good knowlege of how to construct block device stack, esp.
> in context of various qcow2 layers, and requires too explicit configuration.
> More, quite some constructs does not work with -blockdev, - for example
> this is -snapshot.
>
> Instead of "recommended" word, use another construct here.

Could we expand the images section:

  https://qemu.readthedocs.io/en/latest/system/images.html

to give a better overview of when you should use -device/-blockdev vs -drive?

>
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
> ---
>  qemu-options.hx | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 59bdf67a2c..8fe31b465d 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1143,7 +1143,7 @@ have gone through several iterations as the feature set and complexity
>  of the block layer have grown. Many online guides to QEMU often
>  reference older and deprecated options, which can lead to confusion.
>  
> -The recommended modern way to describe disks is to use a combination of
> +The low-level detailed way to describe disks is to use a combination of
>  ``-device`` to specify the hardware device and ``-blockdev`` to
>  describe the backend. The device defines what the guest sees and the
>  backend describes how QEMU handles the data.

How about:

  The most explicit way to describe disks is to use a combination of
  ``-device`` to specify the hardware device and ``-blockdev`` to
  describe the backend. The device defines what the guest sees and the
  backend describes how QEMU handles the data. The ``--drive`` option
  combines the device and backend into a single command line options which
  is useful in the majority of cases. Older options like ``-hda`` make a
  bake in a lot of assumptions from the days when QEMU was emulating a
  legacy PC, they are not recommended for modern configurations.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro