For finding the best matching CPU model for a given set of features
while we don't know the CPU signature (i.e., when computing a baseline
CPU model) we've been using a "shortest list of features" heuristics.
This works well if new CPU models are supersets of older models, but
that's not always the case. As a result it may actually select a new CPU
model as a baseline while removing some features from it to make it
compatible with older models. This is in general worse than using an old
CPU model with a bunch of added features as a guest OS or apps may crash
when using features that were disabled.
On the other hand we don't want to end up with a very old model which
would guarantee no disabled features as it could stop a guest OS or apps
from using some features provided by the CPU because they would not
expect them on such an old CPU.
This patch changes the heuristics to something in between. Enabled and
disabled features are counted separately so that a CPU model requiring
some features to be disabled looks worse than a model with fewer
disabled features even if its complete list of features is longer. The
penalty given for each additional disabled feature gets bigger to make
longer list of disabled features look even worse.
https://bugzilla.redhat.com/show_bug.cgi?id=1851227
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
We currently use -machine accel=XXX which is just a syntax sugar
for -accel XXX. The former doesn't allow specifying arguments for
accelerator, because all arguments passed to -machine are
treated as arguments of machine itself.
The -accel argument was introduced in QEMU commit
v2.9.0-rc0~70^2~19 and since our minimum required version is
newer (2.11.0) we can safely assume its existence and use it
without any capability.
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/233
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Tested-by: Kashyap Chamarthy <kchamart@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
QEMU switched from using underscores in x86 CPU features to hyphens
in the 2.8.0 series with two commits
commit fc7dfd205f3287893c436d932a167bffa30579c8 (HEAD, refs/bisect/bad)
Author: Eduardo Habkost <ehabkost@redhat.com>
Date: Fri Sep 30 15:49:40 2016 -0300
target-i386: Remove underscores from feat_names arrays
commit 54b8dc7c19cd781e96f1e9b001ca6001d804eb19
Author: Eduardo Habkost <ehabkost@redhat.com>
Date: Fri Sep 30 15:49:38 2016 -0300
target-i386: Register aliases for feature names with underscores
Libvirt names use underscores so we conditionally tranlate the
names when talking to new QEMU. Since the min QEMU was raised to
version 2.11.0, all QEMU versions we talk to expect hypens, so
the translation can be done unconditionally.
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
virCommandToString has the possibility to return an already wrapped
string with better format than what we get from the test wrapper script.
The main advantage is that arguments for an option are always on the
same line which makes it more easy to see what changed in a diff and
prevents re-wrapping of the line if a wrapping point moves over the
threshold.
Additionally the used output is the same we have in the VM log file when
a VM is starting.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
The preferred syntax for boolean options is to set the value "on" or
"off". QEMU 7.1.0 will deprecate the short format we currently use.
The long format has been supported with -chardev since at least 1.5.3,
so we don't need to check for it.
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The feature is never enabled by default on KVM and QEMU dropped it from
the models long ago.
https://bugzilla.redhat.com/show_bug.cgi?id=1798004
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Tim Wiederhake <twiederh@redhat.com>
Newer QEMU will translate the feature names to their canonical names so
4.0.0 is the last one which produces the results we currently have in
*-latest.args.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
