On Tue, Mar 07, 2017 at 10:02:26AM +0100, Thomas Huth wrote: > On 03.03.2017 15:58, Eduardo Habkost wrote: > [...] > > I am not convinced that the output of "-cpu help" and > > "-cpu help -machine accel=kvm" should look different. Do you have > > an example of what exactly is wrong with the output currently? > > The problem is that on POWER, we've got a "family" of CPUs with > different sub-types, e.g. for POWER8: > > $ qemu-system-ppc64 -cpu ? | grep POWER8 > PowerPC POWER8E_v2.1 PVR 004b0201 > PowerPC POWER8E (alias for POWER8E_v2.1) > PowerPC POWER8NVL_v1.0 PVR 004c0100 > PowerPC POWER8NVL (alias for POWER8NVL_v1.0) > PowerPC POWER8_v2.0 PVR 004d0200 > PowerPC POWER8 (alias for POWER8_v2.0) > > Most of the users don't know about the current subtype that they are > using, and just want to use "-cpu POWER8" - and for example we've also > got an agreement with the libvirt folks that they can always use "-cpu > POWER8" for any kind of POWER8 system, no matter whether the host is > using a POWER8E or POWER8NVL chip. > So the "POWER8" alias now gets updated internally in QEMU to the correct > host CPU type ... but the output of "-cpu help" is then still wrong. > I agree that it's kind of ugly to have different help texts depending on > whether "accel=kvm" has been used or not, but that sounds still better > to me than printing wrong information here.
I agree that incorrect information is even worse than showing different help information depending on accel=kvm, but: > Thinking about this again ... maybe it would be better if we'd rework > the help text to print out something like this instead: > > PowerPC POWER8 (alias for any POWER8 chip) > > ... so that we simply get rid of the version/subtype information here > completely? Yes, making help output not depend on accel=kvm sounds better to me. This seems to be affected only by the alias table, so it can be fixed even before we address the late-type_register() issue I was discussing with David? -- Eduardo
