On Fri, Dec 06, 2019 at 04:34:31PM -0500, Wainer dos Santos Moschetta wrote:
> Since commit cbe6d6365a48 the command `qemu -accel help` returns
> the list of accelerators enabled in the QEMU binary. This adds
> the list_accel() method which return that same list.
>
> Signed-off-by: Wainer dos Santos Moschetta <waine...@redhat.com>
> Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
> ---
> python/qemu/accel.py | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/python/qemu/accel.py b/python/qemu/accel.py
> index cbeac10dd1..746b7e68f5 100644
> --- a/python/qemu/accel.py
> +++ b/python/qemu/accel.py
> @@ -14,7 +14,11 @@ accelerators.
> # the COPYING file in the top-level directory.
> #
>
> +import logging
> import os
> +import subprocess
> +
> +LOG = logging.getLogger(__name__)
>
> # Mapping host architecture to any additional architectures it can
> # support which often includes its 32 bit cousin.
> @@ -23,6 +27,25 @@ ADDITIONAL_ARCHES = {
> "aarch64" : "armhf"
> }
>
> +def list_accel(qemu_bin):
> + """
> + List accelerators enabled in the QEMU binary.
> +
> + @param qemu_bin (str): path to the QEMU binary.
> + @raise Exception: if failed to run `qemu -accel help`
> + @return a list of accelerator names.
> + """
> + if not qemu_bin:
> + return []
> + try:
> + out = subprocess.check_output("%s -accel help" % qemu_bin,
> shell=True)
There's no need to use a shell here. This could become:
out = subprocess.check_output([qemu_bin, '-accel' 'help'])
> + except:
> + LOG.debug("Failed to get the list of accelerators in %s" % qemu_bin)
> + raise
> + lines = out.decode().splitlines()
And maybe discard the first line earlier with:
lines = out.decode().splitlines()[1:]
Also, you could avoid the manual decode() with the `universal_newlines`
option to subprocess.check_output(), ie:
accels = subprocess.check_output([qemu-bin, '-accel', 'help'],
universal_newlines=True).splitlines()[1:]
> + # Skip the first line which is the header.
> + return [l.strip() for l in lines[1:] if l]
> +
I think that the `if l` check can actually hide undesirable behavior
(bugs) in the `qemu -accel ?` output. I don't remember seeing
`-$(option) ?` returning empty strings but doesn't mean it couldn't
and shouldn't).
I do remember `-machine ?` returning random non-printable characters
that turned out to be a bug, though.
> def kvm_available(target_arch=None):
> host_arch = os.uname()[4]
> if target_arch and target_arch != host_arch:
> --
> 2.21.0
>
- Cleber.
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