Priority of -accel (was: [PATCH] tests/qemu-iotests: Update tests to recent desugarized -accel option)

[Thomas Huth <thuth@redhat.com>]

On 06/01/2020 14.09, Philippe Mathieu-Daudé wrote:
> Commit 6f6e1698a6 desugarized "-machine accel=" to a list
> of "-accel" options. Since now "-machine accel" and "-accel"
> became incompatible, update the iotests to the new format.
> 
> Error reported here:
> https://gitlab.com/qemu-project/qemu/-/jobs/385801004#L3400
> 
> Reported-by: GitLab CI
> Fixes: 6f6e1698a6 (vl: configure accelerators from -accel options)
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  tests/qemu-iotests/235   | 2 +-
>  tests/qemu-iotests/check | 6 +++---
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/tests/qemu-iotests/235 b/tests/qemu-iotests/235
> index fedd111fd4..3d7533980d 100755
> --- a/tests/qemu-iotests/235
> +++ b/tests/qemu-iotests/235
> @@ -49,7 +49,7 @@ qemu_img_create('-f', iotests.imgfmt, '-o', 'preallocation=metadata', disk,
>                  str(size))
>  
>  vm = QEMUMachine(iotests.qemu_prog)
> -vm.add_args('-machine', 'accel=kvm:tcg')
> +vm.add_args('-accel', 'kvm', '-accel', 'tcg')

Looking at this, I wonder whether we really want the "-accel" option to
prioritize the accelerators in the order of appearance? A lot of other
CLI tools give the highest priority to the last parameter instead, e.g.
"gcc -O3 -O1" compiles with -O1, and not with -O3.

Also I think it might be quite common that there are shell scripts which
call "qemu-system-xxx -accel xyz $*" ... and if we don't invert the
priorities of -accel, it will be impossible to override -accel in that
case...

 Thomas