On Do, 2016-12-01 at 18:06 +0100, Laszlo Ersek wrote: > We'd like to raise the value of FW_CFG_FILE_SLOTS. Doing it naively could > lead to problems with backward migration: a more recent QEMU (running an > older machine type) would allow the guest, in fw_cfg_select(), to select a > high key value that is unavailable in the same machine type implemented by > the older (target) QEMU.
I don't think we need this. fw_cfg changes are guest-visible so they must not happen for a given machine type. So if current machine types don't hit the limit that should continue to be the case even if we simply raise FW_CFG_FILE_SLOTS. But we have to take care that new files show up on new machine types only. cheers, Gerd
