On Tue, Aug 27, 2013 at 09:51:22AM +0200, Markus Armbruster wrote: > "Michael S. Tsirkin" <m...@redhat.com> writes: > > > We have a lot of code duplication between machine types, > > this increases with each new machine type > > and each new field. > > > > This has already introduced a minor bug: description > > for pc-1.3 says "Standard PC" while description for > > pc-1.4 is "Standard PC (i440FX + PIIX, 1996)" > > which makes you think 1.3 is somehow more standard, > > or newer, while in fact it's a revision of the same PC. > > I wouldn't call it a bug. We're in the habit of never changing old > machine types, so when we created pc-i440fx-1.4 and pc-q35-1.4 with a > .desc that clearly explains the difference, we didn't change the older > versions the PC machine types as well. > > That may have been overly cautious. As long as .desc is not exposed to > the guest, it's not ABI, thus can be changed.
I just confirmed that on qemu-system-x86_64 the only place where .desc is used is on the machine_parse() help/error code at vl.c. I don't know about other architectures. I suggest we explicitly document the field as a human-readable machine-type description that should be never exposed to the guest (just in case somebody decides to use .desc on some guest-visible table one day). -- Eduardo
