On Mon, Oct 28, 2024 at 05:05:44PM +0100, Cornelia Huck wrote: > On Fri, Oct 25 2024, Daniel P. Berrangé <berra...@redhat.com> wrote: > > > On Fri, Oct 25, 2024 at 03:28:35PM +0200, Eric Auger wrote: > >> Hi Daniel, > >> > >> On 10/25/24 15:13, Daniel P. Berrangé wrote: > >> > On Fri, Oct 25, 2024 at 12:17:40PM +0200, Eric Auger wrote: > >> >> From: Cornelia Huck <coh...@redhat.com> > >> >> > >> >> Add some documentation for the custom model. > >> >> > >> >> Signed-off-by: Eric Auger <eric.au...@redhat.com> > >> >> Signed-off-by: Cornelia Huck <coh...@redhat.com> > >> >> --- > >> >> docs/system/arm/cpu-features.rst | 55 +++++++++++++++++++++++++++----- > >> >> 1 file changed, 47 insertions(+), 8 deletions(-) > >> > > >> >> @@ -167,6 +196,16 @@ disabling many SVE vector lengths would be quite > >> >> verbose, the ``sve<N>`` CPU > >> >> properties have special semantics (see "SVE CPU Property Parsing > >> >> Semantics"). > >> >> > >> >> +The ``custom`` CPU model needs to be configured via individual ID > >> >> register > >> >> +field properties, for example:: > >> >> + > >> >> + $ qemu-system-aarch64 -M virt -cpu > >> >> custom,SYSREG_ID_AA64ISAR0_EL1_DP=0x0 > >> >> + > >> >> +This forces ID_AA64ISAR0_EL1 DP field to 0. > >> > What is the "baseline" featureset implied by 'custom' ? > >> there is no baseline at the moment. By default this is a host > >> passthrough model. > > > > Why do we need to create "custom" at all, as opposed to just letting > > users toggle features on "-cpu host" ? > > We could consolidate that to the current "host" model, once we figure > out how to handle the currently already existing properties. Models > based on the different architecture extensions would probably be more > useable in the long run; maybe "custom" has a place for testing.
If you can set the features against "host", then any testing could be done with "host" surely, making 'custom' pointless ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
