On Tue, Sep 23, 2014 at 09:59:17AM +0200, Markus Armbruster wrote: > "Michael S. Tsirkin" <mst@xxxxxxxxxx> writes: > > > On Mon, Sep 22, 2014 at 05:32:16PM +0200, Markus Armbruster wrote: > >> "Michael S. Tsirkin" <mst@xxxxxxxxxx> writes: > >> > >> > On Sun, Sep 21, 2014 at 03:38:59PM +0100, Alex Bligh wrote: > >> >> Add a configure option --enable-pc-1-0-qemu-kvm and the > >> >> corresponding --disable-pc-1-0-qemu-kvm, defaulting > >> >> to disabled. > >> >> > >> >> Rename machine type pc-1.0 to pc-1.0-qemu-git. > >> >> > >> >> Make pc-1.0 machine type an alias of either pc-1.0-qemu-kvm > >> >> or pc-1.0-qemu-git depending on the value of the config > >> >> option. > >> >> > >> >> Signed-off-by: Alex Bligh <alex@xxxxxxxxxxx> > >> > > >> > I have to say, this one bothers me. > >> > We end up not being able to predict what does pc-1.0 > >> > reference. > >> > > >> > Users also don't get qemu from git so I don't see > >> > why does git make sense in the name? > >> > > >> > Legacy management applications invoked qemu as qemu-kvm - > >> > how about detecting that name and switching > >> > the machine types? > >> > >> Ugh! I like that even less than a configure option. > > > > configure options are tested even less than runtime ones: > > each distro has to pick up a set of options and all > > users are stuck with it. > > So let's assume Ubuntu sets this and something is broken. How is a > > Fedora user to test this? Find out configure flags that Ubuntu uses > > and rebuild from source? It's hard to get people to triage bugs as it > > is. > > That's why changing behaviour in subtle ways depending on > > configure options is a very bad idea. > > All it changes is a default machine type. I wouldn't classify that as > "very bad". Fortunately, our difference of opinion doesn't matter, > because the conclusion of the thread is "leave it to the distros". > > > So a flag might be better, but if we want to be compatible > > with qemu-kvm, poking at argv[0] still better than configure. > > That I do consider a genuinely bad idea. > > Example of usage messed up by it: I symlink from my ~/bin to executables > in various build trees. If one of these programs changed behavior > depending on what it finds in argv[0], I'd have to know *exactly* how it > matches argv[0] to choose suitable names for my symlinks. > > The name "qemu-kvm" is not a useful indicator of compatibility with the > qemu-kvm fork of QEMU anyway. There are programs out there calling > themselves qemu-kvm that aren't compatible with the qemu-kvm fork. And > there are programs out there that are compatible, but call themselves > something else. I think the approach v4 takes is reasonable, though. I didn't look at the implementation yet. -- MST -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list